// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

// See http://dev.chromium.org/developers/design-documents/multi-process-resource-loading

#include "content/browser/loader/resource_dispatcher_host_impl.h"

#include <set>
#include <vector>

#include "base/bind.h"
#include "base/bind_helpers.h"
#include "base/command_line.h"
#include "base/compiler_specific.h"
#include "base/debug/alias.h"
#include "base/logging.h"
#include "base/memory/scoped_ptr.h"
#include "base/memory/shared_memory.h"
#include "base/message_loop/message_loop.h"
#include "base/metrics/histogram.h"
#include "base/metrics/sparse_histogram.h"
#include "base/stl_util.h"
#include "base/third_party/dynamic_annotations/dynamic_annotations.h"
#include "content/browser/appcache/chrome_appcache_service.h"
#include "content/browser/cert_store_impl.h"
#include "content/browser/child_process_security_policy_impl.h"
#include "content/browser/cross_site_request_manager.h"
#include "content/browser/download/download_resource_handler.h"
#include "content/browser/download/save_file_manager.h"
#include "content/browser/download/save_file_resource_handler.h"
#include "content/browser/fileapi/chrome_blob_storage_context.h"
#include "content/browser/loader/async_resource_handler.h"
#include "content/browser/loader/buffered_resource_handler.h"
#include "content/browser/loader/cross_site_resource_handler.h"
#include "content/browser/loader/power_save_block_resource_throttle.h"
#include "content/browser/loader/redirect_to_file_resource_handler.h"
#include "content/browser/loader/resource_message_filter.h"
#include "content/browser/loader/resource_request_info_impl.h"
#include "content/browser/loader/stream_resource_handler.h"
#include "content/browser/loader/sync_resource_handler.h"
#include "content/browser/loader/throttling_resource_handler.h"
#include "content/browser/loader/upload_data_stream_builder.h"
#include "content/browser/plugin_service_impl.h"
#include "content/browser/renderer_host/render_view_host_delegate.h"
#include "content/browser/renderer_host/render_view_host_impl.h"
#include "content/browser/resource_context_impl.h"
#include "content/browser/streams/stream.h"
#include "content/browser/streams/stream_context.h"
#include "content/browser/streams/stream_registry.h"
#include "content/browser/worker_host/worker_service_impl.h"
#include "content/common/resource_messages.h"
#include "content/common/ssl_status_serialization.h"
#include "content/common/view_messages.h"
#include "content/public/browser/browser_thread.h"
#include "content/public/browser/content_browser_client.h"
#include "content/public/browser/download_manager.h"
#include "content/public/browser/download_url_parameters.h"
#include "content/public/browser/global_request_id.h"
#include "content/public/browser/resource_dispatcher_host_delegate.h"
#include "content/public/browser/resource_request_details.h"
#include "content/public/browser/resource_throttle.h"
#include "content/public/browser/stream_handle.h"
#include "content/public/browser/user_metrics.h"
#include "content/public/common/content_switches.h"
#include "content/public/common/process_type.h"
#include "content/public/common/url_constants.h"
#include "ipc/ipc_message_macros.h"
#include "ipc/ipc_message_start.h"
#include "net/base/auth.h"
#include "net/base/load_flags.h"
#include "net/base/mime_util.h"
#include "net/base/net_errors.h"
#include "net/base/registry_controlled_domains/registry_controlled_domain.h"
#include "net/base/request_priority.h"
#include "net/base/upload_data_stream.h"
#include "net/cert/cert_status_flags.h"
#include "net/cookies/cookie_monster.h"
#include "net/http/http_response_headers.h"
#include "net/http/http_response_info.h"
#include "net/ssl/ssl_cert_request_info.h"
#include "net/url_request/url_request.h"
#include "net/url_request/url_request_context.h"
#include "net/url_request/url_request_job_factory.h"
#include "webkit/browser/appcache/appcache_interceptor.h"
#include "webkit/common/blob/blob_data.h"
#include "webkit/browser/blob/blob_data_handle.h"
#include "webkit/browser/blob/blob_storage_context.h"
#include "webkit/browser/blob/blob_url_request_job_factory.h"
#include "webkit/browser/fileapi/file_permission_policy.h"
#include "webkit/browser/fileapi/file_system_context.h"
#include "webkit/common/appcache/appcache_interfaces.h"
#include "webkit/common/blob/shareable_file_reference.h"
#include "webkit/common/resource_request_body.h"

using base::Time;
using base::TimeDelta;
using base::TimeTicks;
using webkit_blob::ShareableFileReference;
using webkit_glue::ResourceRequestBody;

// ----------------------------------------------------------------------------

namespace content {

namespace {

static ResourceDispatcherHostImpl* g_resource_dispatcher_host;

// The interval for calls to ResourceDispatcherHostImpl::UpdateLoadStates
const int kUpdateLoadStatesIntervalMsec = 100;

// Maximum byte "cost" of all the outstanding requests for a renderer.
// See delcaration of |max_outstanding_requests_cost_per_process_| for details.
// This bound is 25MB, which allows for around 6000 outstanding requests.
const int kMaxOutstandingRequestsCostPerProcess = 26214400;

// The number of milliseconds after noting a user gesture that we will
// tag newly-created URLRequest objects with the
// net::LOAD_MAYBE_USER_GESTURE load flag. This is a fairly arbitrary
// guess at how long to expect direct impact from a user gesture, but
// this should be OK as the load flag is a best-effort thing only,
// rather than being intended as fully accurate.
const int kUserGestureWindowMs = 3500;

// Ratio of |max_num_in_flight_requests_| that any one renderer is allowed to
// use. Arbitrarily chosen.
const double kMaxRequestsPerProcessRatio = 0.45;

bool IsDetachableResourceType(ResourceType::Type type) {
  switch (type) {
    case ResourceType::PREFETCH:
      return true;
    default:
      return false;
  }
}

// Aborts a request before an URLRequest has actually been created.
void AbortRequestBeforeItStarts(ResourceMessageFilter* filter,
                                IPC::Message* sync_result,
                                int request_id) {
  if (sync_result) {
    SyncLoadResult result;
    result.error_code = net::ERR_ABORTED;
    ResourceHostMsg_SyncLoad::WriteReplyParams(sync_result, result);
    filter->Send(sync_result);
  } else {
    // Tell the renderer that this request was disallowed.
    filter->Send(new ResourceMsg_RequestComplete(
        request_id,
        net::ERR_ABORTED,
        false,
        std::string(),   // No security info needed, connection not established.
        base::TimeTicks()));
  }
}

void SetReferrerForRequest(net::URLRequest* request, const Referrer& referrer) {
  if (!referrer.url.is_valid() ||
      CommandLine::ForCurrentProcess()->HasSwitch(switches::kNoReferrers)) {
    request->SetReferrer(std::string());
  } else {
    request->SetReferrer(referrer.url.spec());
  }

  net::URLRequest::ReferrerPolicy net_referrer_policy =
      net::URLRequest::CLEAR_REFERRER_ON_TRANSITION_FROM_SECURE_TO_INSECURE;
  switch (referrer.policy) {
    case WebKit::WebReferrerPolicyDefault:
      net_referrer_policy =
          net::URLRequest::CLEAR_REFERRER_ON_TRANSITION_FROM_SECURE_TO_INSECURE;
      break;
    case WebKit::WebReferrerPolicyAlways:
    case WebKit::WebReferrerPolicyNever:
    case WebKit::WebReferrerPolicyOrigin:
      net_referrer_policy = net::URLRequest::NEVER_CLEAR_REFERRER;
      break;
  }
  request->set_referrer_policy(net_referrer_policy);
}

// Consults the RendererSecurity policy to determine whether the
// ResourceDispatcherHostImpl should service this request.  A request might be
// disallowed if the renderer is not authorized to retrieve the request URL or
// if the renderer is attempting to upload an unauthorized file.
bool ShouldServiceRequest(int process_type,
                          int child_id,
                          const ResourceHostMsg_Request& request_data,
                          fileapi::FileSystemContext* file_system_context)  {
  if (process_type == PROCESS_TYPE_PLUGIN)
    return true;

  ChildProcessSecurityPolicyImpl* policy =
      ChildProcessSecurityPolicyImpl::GetInstance();

  // Check if the renderer is permitted to request the requested URL.
  if (!policy->CanRequestURL(child_id, request_data.url)) {
    VLOG(1) << "Denied unauthorized request for "
            << request_data.url.possibly_invalid_spec();
    return false;
  }

  // Check if the renderer is permitted to upload the requested files.
  if (request_data.request_body.get()) {
    const std::vector<ResourceRequestBody::Element>* uploads =
        request_data.request_body->elements();
    std::vector<ResourceRequestBody::Element>::const_iterator iter;
    for (iter = uploads->begin(); iter != uploads->end(); ++iter) {
      if (iter->type() == ResourceRequestBody::Element::TYPE_FILE &&
          !policy->CanReadFile(child_id, iter->path())) {
        NOTREACHED() << "Denied unauthorized upload of "
                     << iter->path().value();
        return false;
      }
      if (iter->type() == ResourceRequestBody::Element::TYPE_FILE_FILESYSTEM) {
        fileapi::FileSystemURL url =
            file_system_context->CrackURL(iter->filesystem_url());
        if (!policy->CanReadFileSystemFile(child_id, url)) {
          NOTREACHED() << "Denied unauthorized upload of "
                       << iter->filesystem_url().spec();
          return false;
        }
      }
    }
  }

  return true;
}

void RemoveDownloadFileFromChildSecurityPolicy(int child_id,
                                               const base::FilePath& path) {
  ChildProcessSecurityPolicyImpl::GetInstance()->RevokeAllPermissionsForFile(
      child_id, path);
}

#if defined(OS_WIN)
#pragma warning(disable: 4748)
#pragma optimize("", off)
#endif

#if defined(OS_WIN)
#pragma optimize("", on)
#pragma warning(default: 4748)
#endif

net::Error CallbackAndReturn(
    const DownloadUrlParameters::OnStartedCallback& started_cb,
    net::Error net_error) {
  if (started_cb.is_null())
    return net_error;
  BrowserThread::PostTask(
      BrowserThread::UI, FROM_HERE,
      base::Bind(started_cb, static_cast<DownloadItem*>(NULL), net_error));

  return net_error;
}

int GetCertID(net::URLRequest* request, int child_id) {
  if (request->ssl_info().cert.get()) {
    return CertStore::GetInstance()->StoreCert(request->ssl_info().cert.get(),
                                               child_id);
  }
  return 0;
}

void NotifyRedirectOnUI(int render_process_id,
                        int render_view_id,
                        scoped_ptr<ResourceRedirectDetails> details) {
  RenderViewHostImpl* host =
      RenderViewHostImpl::FromID(render_process_id, render_view_id);
  if (!host)
    return;

  RenderViewHostDelegate* delegate = host->GetDelegate();
  delegate->DidGetRedirectForResourceRequest(*details.get());
}

void NotifyResponseOnUI(int render_process_id,
                        int render_view_id,
                        scoped_ptr<ResourceRequestDetails> details) {
  RenderViewHostImpl* host =
      RenderViewHostImpl::FromID(render_process_id, render_view_id);
  if (!host)
    return;

  RenderViewHostDelegate* delegate = host->GetDelegate();
  delegate->DidGetResourceResponseStart(*details.get());
}

}  // namespace

// static
ResourceDispatcherHost* ResourceDispatcherHost::Get() {
  return g_resource_dispatcher_host;
}

ResourceDispatcherHostImpl::ResourceDispatcherHostImpl()
    : save_file_manager_(new SaveFileManager()),
      request_id_(-1),
      is_shutdown_(false),
      num_in_flight_requests_(0),
      max_num_in_flight_requests_(base::SharedMemory::GetHandleLimit()),
      max_num_in_flight_requests_per_process_(
          static_cast<int>(
              max_num_in_flight_requests_ * kMaxRequestsPerProcessRatio)),
      max_outstanding_requests_cost_per_process_(
          kMaxOutstandingRequestsCostPerProcess),
      filter_(NULL),
      delegate_(NULL),
      allow_cross_origin_auth_prompt_(false) {
  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
  DCHECK(!g_resource_dispatcher_host);
  g_resource_dispatcher_host = this;

  GetContentClient()->browser()->ResourceDispatcherHostCreated();

  ANNOTATE_BENIGN_RACE(
      &last_user_gesture_time_,
      "We don't care about the precise value, see http://crbug.com/92889");

  BrowserThread::PostTask(BrowserThread::IO,
                          FROM_HERE,
                          base::Bind(&ResourceDispatcherHostImpl::OnInit,
                                     base::Unretained(this)));

  update_load_states_timer_.reset(
      new base::RepeatingTimer<ResourceDispatcherHostImpl>());
}

ResourceDispatcherHostImpl::~ResourceDispatcherHostImpl() {
  DCHECK(outstanding_requests_stats_map_.empty());
  DCHECK(g_resource_dispatcher_host);
  g_resource_dispatcher_host = NULL;
}

// static
ResourceDispatcherHostImpl* ResourceDispatcherHostImpl::Get() {
  return g_resource_dispatcher_host;
}

void ResourceDispatcherHostImpl::SetDelegate(
    ResourceDispatcherHostDelegate* delegate) {
  delegate_ = delegate;
}

void ResourceDispatcherHostImpl::SetAllowCrossOriginAuthPrompt(bool value) {
  allow_cross_origin_auth_prompt_ = value;
}

void ResourceDispatcherHostImpl::AddResourceContext(ResourceContext* context) {
  active_resource_contexts_.insert(context);
}

void ResourceDispatcherHostImpl::RemoveResourceContext(
    ResourceContext* context) {
  CHECK(ContainsKey(active_resource_contexts_, context));
  active_resource_contexts_.erase(context);
}

void ResourceDispatcherHostImpl::CancelRequestsForContext(
    ResourceContext* context) {
  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
  DCHECK(context);

  CHECK(ContainsKey(active_resource_contexts_, context));

  // Note that request cancellation has side effects. Therefore, we gather all
  // the requests to cancel first, and then we start cancelling. We assert at
  // the end that there are no more to cancel since the context is about to go
  // away.
  typedef std::vector<linked_ptr<ResourceLoader> > LoaderList;
  LoaderList loaders_to_cancel;

  for (LoaderMap::iterator i = pending_loaders_.begin();
       i != pending_loaders_.end();) {
    if (i->second->GetRequestInfo()->GetContext() == context) {
      loaders_to_cancel.push_back(i->second);
      IncrementOutstandingRequestsMemory(-1, *i->second->GetRequestInfo());
      pending_loaders_.erase(i++);
    } else {
      ++i;
    }
  }

  for (BlockedLoadersMap::iterator i = blocked_loaders_map_.begin();
       i != blocked_loaders_map_.end();) {
    BlockedLoadersList* loaders = i->second;
    if (loaders->empty()) {
      // This can happen if BlockRequestsForRoute() has been called for a route,
      // but we haven't blocked any matching requests yet.
      ++i;
      continue;
    }
    ResourceRequestInfoImpl* info = loaders->front()->GetRequestInfo();
    if (info->GetContext() == context) {
      blocked_loaders_map_.erase(i++);
      for (BlockedLoadersList::const_iterator it = loaders->begin();
           it != loaders->end(); ++it) {
        linked_ptr<ResourceLoader> loader = *it;
        info = loader->GetRequestInfo();
        // We make the assumption that all requests on the list have the same
        // ResourceContext.
        DCHECK_EQ(context, info->GetContext());
        IncrementOutstandingRequestsMemory(-1, *info);
        loaders_to_cancel.push_back(loader);
      }
      delete loaders;
    } else {
      ++i;
    }
  }

#ifndef NDEBUG
  for (LoaderList::iterator i = loaders_to_cancel.begin();
       i != loaders_to_cancel.end(); ++i) {
    // There is no strict requirement that this be the case, but currently
    // downloads, streams, detachable requests, and transferred requests are the
    // only requests that aren't cancelled when the associated processes go
    // away. It may be OK for this invariant to change in the future, but if
    // this assertion fires without the invariant changing, then it's indicative
    // of a leak.
    DCHECK(
        (*i)->GetRequestInfo()->is_download() ||
        (*i)->GetRequestInfo()->is_stream() ||
        (*i)->GetRequestInfo()->is_detached() ||
        (*i)->is_transferring());
  }
#endif

  loaders_to_cancel.clear();

  // Validate that no more requests for this context were added.
  for (LoaderMap::const_iterator i = pending_loaders_.begin();
       i != pending_loaders_.end(); ++i) {
    // http://crbug.com/90971
    CHECK_NE(i->second->GetRequestInfo()->GetContext(), context);
  }

  for (BlockedLoadersMap::const_iterator i = blocked_loaders_map_.begin();
       i != blocked_loaders_map_.end(); ++i) {
    BlockedLoadersList* loaders = i->second;
    if (!loaders->empty()) {
      ResourceRequestInfoImpl* info = loaders->front()->GetRequestInfo();
      // http://crbug.com/90971
      CHECK_NE(info->GetContext(), context);
    }
  }
}

net::Error ResourceDispatcherHostImpl::BeginDownload(
    scoped_ptr<net::URLRequest> request,
    const Referrer& referrer,
    bool is_content_initiated,
    ResourceContext* context,
    int child_id,
    int route_id,
    bool prefer_cache,
    scoped_ptr<DownloadSaveInfo> save_info,
    uint32 download_id,
    const DownloadStartedCallback& started_callback) {
  if (is_shutdown_)
    return CallbackAndReturn(started_callback, net::ERR_INSUFFICIENT_RESOURCES);

  const GURL& url = request->original_url();

  // http://crbug.com/90971
  char url_buf[128];
  base::strlcpy(url_buf, url.spec().c_str(), arraysize(url_buf));
  base::debug::Alias(url_buf);
  CHECK(ContainsKey(active_resource_contexts_, context));

  SetReferrerForRequest(request.get(), referrer);

  int extra_load_flags = net::LOAD_IS_DOWNLOAD;
  if (prefer_cache) {
    // If there is upload data attached, only retrieve from cache because there
    // is no current mechanism to prompt the user for their consent for a
    // re-post. For GETs, try to retrieve data from the cache and skip
    // validating the entry if present.
    if (request->get_upload() != NULL)
      extra_load_flags |= net::LOAD_ONLY_FROM_CACHE;
    else
      extra_load_flags |= net::LOAD_PREFERRING_CACHE;
  } else {
    extra_load_flags |= net::LOAD_DISABLE_CACHE;
  }
  request->set_load_flags(request->load_flags() | extra_load_flags);

  // No need to get offline load flags for downloads, but make sure
  // we have an OfflinePolicy to receive request completions.
  GlobalRoutingID id(child_id, route_id);
  if (!offline_policy_map_[id])
    offline_policy_map_[id] = new OfflinePolicy();

  // Check if the renderer is permitted to request the requested URL.
  if (!ChildProcessSecurityPolicyImpl::GetInstance()->
          CanRequestURL(child_id, url)) {
    VLOG(1) << "Denied unauthorized download request for "
            << url.possibly_invalid_spec();
    return CallbackAndReturn(started_callback, net::ERR_ACCESS_DENIED);
  }

  request_id_--;

  const net::URLRequestContext* request_context = context->GetRequestContext();
  if (!request_context->job_factory()->IsHandledURL(url)) {
    VLOG(1) << "Download request for unsupported protocol: "
            << url.possibly_invalid_spec();
    return CallbackAndReturn(started_callback, net::ERR_ACCESS_DENIED);
  }

  ResourceRequestInfoImpl* extra_info =
      CreateRequestInfo(child_id, route_id, true, context);
  extra_info->AssociateWithRequest(request.get());  // Request takes ownership.

  if (request->url().SchemeIs(chrome::kBlobScheme)) {
    ChromeBlobStorageContext* blob_context =
        GetChromeBlobStorageContextForResourceContext(context);
    webkit_blob::BlobProtocolHandler::SetRequestedBlobDataHandle(
        request.get(),
        blob_context->context()->GetBlobDataFromPublicURL(request->url()));
  }

  // From this point forward, the |DownloadResourceHandler| is responsible for
  // |started_callback|.
  scoped_ptr<ResourceHandler> handler(
      CreateResourceHandlerForDownload(request.get(), is_content_initiated,
                                       true, download_id, save_info.Pass(),
                                       started_callback));

  BeginRequestInternal(request.Pass(), handler.Pass());

  return net::OK;
}

void ResourceDispatcherHostImpl::ClearLoginDelegateForRequest(
    net::URLRequest* request) {
  ResourceRequestInfoImpl* info = ResourceRequestInfoImpl::ForRequest(request);
  if (info) {
    ResourceLoader* loader = GetLoader(info->GetGlobalRequestID());
    if (loader)
      loader->ClearLoginDelegate();
  }
}

void ResourceDispatcherHostImpl::Shutdown() {
  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
  BrowserThread::PostTask(BrowserThread::IO,
                          FROM_HERE,
                          base::Bind(&ResourceDispatcherHostImpl::OnShutdown,
                                     base::Unretained(this)));
}

scoped_ptr<ResourceHandler>
ResourceDispatcherHostImpl::CreateResourceHandlerForDownload(
    net::URLRequest* request,
    bool is_content_initiated,
    bool must_download,
    uint32 id,
    scoped_ptr<DownloadSaveInfo> save_info,
    const DownloadUrlParameters::OnStartedCallback& started_cb) {
  scoped_ptr<ResourceHandler> handler(
      new DownloadResourceHandler(id, request, started_cb, save_info.Pass()));
  if (delegate_) {
    const ResourceRequestInfo* request_info(
        ResourceRequestInfo::ForRequest(request));

    ScopedVector<ResourceThrottle> throttles;
    delegate_->DownloadStarting(
        request, request_info->GetContext(), request_info->GetChildID(),
        request_info->GetRouteID(), request_info->GetRequestID(),
        is_content_initiated, must_download, &throttles);
    if (!throttles.empty()) {
      handler.reset(
          new ThrottlingResourceHandler(
              handler.Pass(), request, throttles.Pass()));
    }
  }
  return handler.Pass();
}

scoped_ptr<ResourceHandler>
ResourceDispatcherHostImpl::MaybeInterceptAsStream(net::URLRequest* request,
                                                   ResourceResponse* response) {
  ResourceRequestInfoImpl* info = ResourceRequestInfoImpl::ForRequest(request);
  const std::string& mime_type = response->head.mime_type;

  GURL origin;
  std::string target_id;
  if (!delegate_ ||
      !delegate_->ShouldInterceptResourceAsStream(info->GetContext(),
                                                  request->url(),
                                                  mime_type,
                                                  &origin,
                                                  &target_id)) {
    return scoped_ptr<ResourceHandler>();
  }

  StreamContext* stream_context =
      GetStreamContextForResourceContext(info->GetContext());

  scoped_ptr<StreamResourceHandler> handler(
      new StreamResourceHandler(request,
                                stream_context->registry(),
                                origin));

  info->set_is_stream(true);
  delegate_->OnStreamCreated(
      info->GetContext(),
      info->GetChildID(),
      info->GetRouteID(),
      target_id,
      handler->stream()->CreateHandle(request->url(), mime_type),
      request->GetExpectedContentSize());
  return handler.PassAs<ResourceHandler>();
}

void ResourceDispatcherHostImpl::ClearSSLClientAuthHandlerForRequest(
    net::URLRequest* request) {
  ResourceRequestInfoImpl* info = ResourceRequestInfoImpl::ForRequest(request);
  if (info) {
    ResourceLoader* loader = GetLoader(info->GetGlobalRequestID());
    if (loader)
      loader->ClearSSLClientAuthHandler();
  }
}

ResourceDispatcherHostLoginDelegate*
ResourceDispatcherHostImpl::CreateLoginDelegate(
    ResourceLoader* loader,
    net::AuthChallengeInfo* auth_info) {
  if (!delegate_)
    return NULL;

  return delegate_->CreateLoginDelegate(auth_info, loader->request());
}

bool ResourceDispatcherHostImpl::AcceptAuthRequest(
    ResourceLoader* loader,
    net::AuthChallengeInfo* auth_info) {
  if (delegate_ && !delegate_->AcceptAuthRequest(loader->request(), auth_info))
    return false;

  return true;
}

bool ResourceDispatcherHostImpl::AcceptSSLClientCertificateRequest(
    ResourceLoader* loader,
    net::SSLCertRequestInfo* cert_info) {
  if (delegate_ && !delegate_->AcceptSSLClientCertificateRequest(
          loader->request(), cert_info)) {
    return false;
  }

  return true;
}

bool ResourceDispatcherHostImpl::HandleExternalProtocol(ResourceLoader* loader,
                                                        const GURL& url) {
  if (!delegate_)
    return false;

  ResourceRequestInfoImpl* info = loader->GetRequestInfo();

  if (!ResourceType::IsFrame(info->GetResourceType()))
    return false;

  const net::URLRequestJobFactory* job_factory =
      info->GetContext()->GetRequestContext()->job_factory();
  if (job_factory->IsHandledURL(url))
    return false;

  return delegate_->HandleExternalProtocol(url, info->GetChildID(),
                                           info->GetRouteID());
}

void ResourceDispatcherHostImpl::DidStartRequest(ResourceLoader* loader) {
  // Make sure we have the load state monitor running
  if (!update_load_states_timer_->IsRunning()) {
    update_load_states_timer_->Start(FROM_HERE,
        TimeDelta::FromMilliseconds(kUpdateLoadStatesIntervalMsec),
        this, &ResourceDispatcherHostImpl::UpdateLoadStates);
  }
}

void ResourceDispatcherHostImpl::DidReceiveRedirect(ResourceLoader* loader,
                                                    const GURL& new_url) {
  ResourceRequestInfoImpl* info = loader->GetRequestInfo();

  int render_process_id, render_view_id;
  if (!info->GetAssociatedRenderView(&render_process_id, &render_view_id))
    return;

  // Notify the observers on the UI thread.
  scoped_ptr<ResourceRedirectDetails> detail(new ResourceRedirectDetails(
      loader->request(),
      GetCertID(loader->request(), info->GetChildID()),
      new_url));
  BrowserThread::PostTask(
      BrowserThread::UI, FROM_HERE,
      base::Bind(
          &NotifyRedirectOnUI,
          render_process_id, render_view_id, base::Passed(&detail)));
}

void ResourceDispatcherHostImpl::DidReceiveResponse(ResourceLoader* loader) {
  ResourceRequestInfoImpl* info = loader->GetRequestInfo();

  // There should be an entry in the map created when we dispatched the
  // request unless it's been detached and the renderer has died.
  OfflineMap::iterator policy_it(
      offline_policy_map_.find(info->GetGlobalRoutingID()));
  if (offline_policy_map_.end() != policy_it) {
    policy_it->second->UpdateStateForSuccessfullyStartedRequest(
        loader->request()->response_info());
  } else {
    // Unless detached, we should have an entry in offline_policy_map_ from
    // when this request traversed Begin{Download,SaveFile,Request}.
    // TODO(rdsmith): This isn't currently true; see http://crbug.com/241176.
    DCHECK(info->is_detached());
  }

  int render_process_id, render_view_id;
  if (!info->GetAssociatedRenderView(&render_process_id, &render_view_id))
    return;

  // Notify the observers on the UI thread.
  scoped_ptr<ResourceRequestDetails> detail(new ResourceRequestDetails(
      loader->request(),
      GetCertID(loader->request(), info->GetChildID())));
  BrowserThread::PostTask(
      BrowserThread::UI, FROM_HERE,
      base::Bind(
          &NotifyResponseOnUI,
          render_process_id, render_view_id, base::Passed(&detail)));
}

void ResourceDispatcherHostImpl::DidFinishLoading(ResourceLoader* loader) {
  ResourceRequestInfo* info = loader->GetRequestInfo();

  // Record final result of all resource loads.
  if (info->GetResourceType() == ResourceType::MAIN_FRAME) {
    // This enumeration has "3" appended to its name to distinguish it from
    // older versions.
    UMA_HISTOGRAM_SPARSE_SLOWLY(
        "Net.ErrorCodesForMainFrame3",
        -loader->request()->status().error());

    if (loader->request()->url().SchemeIsSecure() &&
        loader->request()->url().host() == "www.google.com") {
      UMA_HISTOGRAM_SPARSE_SLOWLY(
          "Net.ErrorCodesForHTTPSGoogleMainFrame2",
          -loader->request()->status().error());
    }
  } else {
    if (info->GetResourceType() == ResourceType::IMAGE) {
      UMA_HISTOGRAM_SPARSE_SLOWLY(
          "Net.ErrorCodesForImages",
          -loader->request()->status().error());
    }
    // This enumeration has "2" appended to distinguish it from older versions.
    UMA_HISTOGRAM_SPARSE_SLOWLY(
        "Net.ErrorCodesForSubresources2",
        -loader->request()->status().error());
  }

  // Destroy the ResourceLoader.
  RemovePendingRequest(info->GetChildID(), info->GetRequestID());
}

// static
bool ResourceDispatcherHostImpl::RenderViewForRequest(
    const net::URLRequest* request,
    int* render_process_id,
    int* render_view_id) {
  const ResourceRequestInfoImpl* info =
      ResourceRequestInfoImpl::ForRequest(request);
  if (!info) {
    *render_process_id = -1;
    *render_view_id = -1;
    return false;
  }

  return info->GetAssociatedRenderView(render_process_id, render_view_id);
}

void ResourceDispatcherHostImpl::OnInit() {
  scheduler_.reset(new ResourceScheduler);
  appcache::AppCacheInterceptor::EnsureRegistered();
}

void ResourceDispatcherHostImpl::OnShutdown() {
  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));

  is_shutdown_ = true;
  pending_loaders_.clear();

  // Make sure we shutdown the timer now, otherwise by the time our destructor
  // runs if the timer is still running the Task is deleted twice (once by
  // the MessageLoop and the second time by RepeatingTimer).
  update_load_states_timer_.reset();

  // Clear blocked requests if any left.
  // Note that we have to do this in 2 passes as we cannot call
  // CancelBlockedRequestsForRoute while iterating over
  // blocked_loaders_map_, as it modifies it.
  std::set<GlobalRoutingID> ids;
  for (BlockedLoadersMap::const_iterator iter = blocked_loaders_map_.begin();
       iter != blocked_loaders_map_.end(); ++iter) {
    std::pair<std::set<GlobalRoutingID>::iterator, bool> result =
        ids.insert(iter->first);
    // We should not have duplicates.
    DCHECK(result.second);
  }
  for (std::set<GlobalRoutingID>::const_iterator iter = ids.begin();
       iter != ids.end(); ++iter) {
    CancelBlockedRequestsForRoute(iter->child_id, iter->route_id);
  }

  scheduler_.reset();
}

bool ResourceDispatcherHostImpl::OnMessageReceived(
    const IPC::Message& message,
    ResourceMessageFilter* filter,
    bool* message_was_ok) {
  filter_ = filter;
  bool handled = true;
  IPC_BEGIN_MESSAGE_MAP_EX(ResourceDispatcherHostImpl, message, *message_was_ok)
    IPC_MESSAGE_HANDLER(ResourceHostMsg_RequestResource, OnRequestResource)
    IPC_MESSAGE_HANDLER_DELAY_REPLY(ResourceHostMsg_SyncLoad, OnSyncLoad)
    IPC_MESSAGE_HANDLER(ResourceHostMsg_ReleaseDownloadedFile,
                        OnReleaseDownloadedFile)
    IPC_MESSAGE_HANDLER(ResourceHostMsg_DataDownloaded_ACK, OnDataDownloadedACK)
    IPC_MESSAGE_HANDLER(ResourceHostMsg_UploadProgress_ACK, OnUploadProgressACK)
    IPC_MESSAGE_HANDLER(ResourceHostMsg_CancelRequest, OnCancelRequest)
    IPC_MESSAGE_UNHANDLED(handled = false)
  IPC_END_MESSAGE_MAP_EX()

  if (!handled && IPC_MESSAGE_ID_CLASS(message.type()) == ResourceMsgStart) {
    PickleIterator iter(message);
    int request_id = -1;
    bool ok = iter.ReadInt(&request_id);
    DCHECK(ok);
    GlobalRequestID id(filter_->child_id(), request_id);
    DelegateMap::iterator it = delegate_map_.find(id);
    if (it != delegate_map_.end()) {
      ObserverList<ResourceMessageDelegate>::Iterator del_it(*it->second);
      ResourceMessageDelegate* delegate;
      while (!handled && (delegate = del_it.GetNext()) != NULL) {
        handled = delegate->OnMessageReceived(message, message_was_ok);
      }
    }
  }

  filter_ = NULL;
  return handled;
}

void ResourceDispatcherHostImpl::OnRequestResource(
    const IPC::Message& message,
    int request_id,
    const ResourceHostMsg_Request& request_data) {
  BeginRequest(request_id, request_data, NULL, message.routing_id());
}

// Begins a resource request with the given params on behalf of the specified
// child process.  Responses will be dispatched through the given receiver. The
// process ID is used to lookup WebContentsImpl from routing_id's in the case of
// a request from a renderer.  request_context is the cookie/cache context to be
// used for this request.
//
// If sync_result is non-null, then a SyncLoad reply will be generated, else
// a normal asynchronous set of response messages will be generated.
void ResourceDispatcherHostImpl::OnSyncLoad(
    int request_id,
    const ResourceHostMsg_Request& request_data,
    IPC::Message* sync_result) {
  BeginRequest(request_id, request_data, sync_result,
               sync_result->routing_id());
}

void ResourceDispatcherHostImpl::UpdateRequestForTransfer(
    int child_id,
    int route_id,
    int request_id,
    const ResourceHostMsg_Request& request_data,
    const linked_ptr<ResourceLoader>& loader) {
  ResourceRequestInfoImpl* info = loader->GetRequestInfo();
  GlobalRoutingID old_routing_id(
      request_data.transferred_request_child_id, info->GetRouteID());
  GlobalRequestID old_request_id(request_data.transferred_request_child_id,
                                 request_data.transferred_request_request_id);
  GlobalRoutingID new_routing_id(child_id, route_id);
  GlobalRequestID new_request_id(child_id, request_id);

  // Clear out data that depends on |info| before updating it.
  IncrementOutstandingRequestsMemory(-1, *info);
  OustandingRequestsStats empty_stats = { 0, 0 };
  OustandingRequestsStats old_stats = GetOutstandingRequestsStats(*info);
  UpdateOutstandingRequestsStats(*info, empty_stats);
  pending_loaders_.erase(old_request_id);

  // ResourceHandlers should always get state related to the request from the
  // ResourceRequestInfo rather than caching it locally.  This lets us update
  // the info object when a transfer occurs.
  info->UpdateForTransfer(child_id, route_id, request_data.origin_pid,
                          request_id, request_data.frame_id,
                          request_data.parent_frame_id, filter_->GetWeakPtr());

  // Update maps that used the old IDs, if necessary.  Some transfers in tests
  // do not actually use a different ID, so not all maps need to be updated.
  pending_loaders_[new_request_id] = loader;
  UpdateOutstandingRequestsStats(*info, old_stats);
  IncrementOutstandingRequestsMemory(1, *info);
  if (old_routing_id != new_routing_id) {
    if (offline_policy_map_.find(old_routing_id) != offline_policy_map_.end()) {
      offline_policy_map_[new_routing_id] = offline_policy_map_[old_routing_id];
      offline_policy_map_.erase(old_routing_id);
    }
    if (blocked_loaders_map_.find(old_routing_id) !=
            blocked_loaders_map_.end()) {
      blocked_loaders_map_[new_routing_id] =
          blocked_loaders_map_[old_routing_id];
      blocked_loaders_map_.erase(old_routing_id);
    }
  }
  if (old_request_id != new_request_id) {
    DelegateMap::iterator it = delegate_map_.find(old_request_id);
    if (it != delegate_map_.end()) {
      // Tell each delegate that the request ID has changed.
      ObserverList<ResourceMessageDelegate>::Iterator del_it(*it->second);
      ResourceMessageDelegate* delegate;
      while ((delegate = del_it.GetNext()) != NULL) {
        delegate->set_request_id(new_request_id);
      }
      // Now store the observer list under the new request ID.
      delegate_map_[new_request_id] = delegate_map_[old_request_id];
      delegate_map_.erase(old_request_id);
    }
  }

  // Notify the delegate to allow it to update state as well.
  if (delegate_) {
    delegate_->WillTransferRequestToNewProcess(old_routing_id.child_id,
                                               old_routing_id.route_id,
                                               old_request_id.request_id,
                                               child_id,
                                               route_id,
                                               request_id);
  }

  // We should have a CrossSiteResourceHandler to finish the transfer.
  DCHECK(info->cross_site_handler());
}

void ResourceDispatcherHostImpl::BeginRequest(
    int request_id,
    const ResourceHostMsg_Request& request_data,
    IPC::Message* sync_result,  // only valid for sync
    int route_id) {
  int process_type = filter_->process_type();
  int child_id = filter_->child_id();

  // Reject invalid priority.
  if (request_data.priority < net::MINIMUM_PRIORITY ||
      request_data.priority > net::MAXIMUM_PRIORITY) {
    RecordAction(UserMetricsAction("BadMessageTerminate_RDH"));
    filter_->BadMessageReceived();
    return;
  }

  // If we crash here, figure out what URL the renderer was requesting.
  // http://crbug.com/91398
  char url_buf[128];
  base::strlcpy(url_buf, request_data.url.spec().c_str(), arraysize(url_buf));
  base::debug::Alias(url_buf);

  // If the request that's coming in is being transferred from another process,
  // we want to reuse and resume the old loader rather than start a new one.
  linked_ptr<ResourceLoader> deferred_loader;
  {
    LoaderMap::iterator it = pending_loaders_.find(
        GlobalRequestID(request_data.transferred_request_child_id,
                        request_data.transferred_request_request_id));
    if (it != pending_loaders_.end()) {
      // If the request is transferring to a new process, we can update our
      // state and let it resume with its existing ResourceHandlers.
      if (it->second->is_transferring()) {
        deferred_loader = it->second;
        UpdateRequestForTransfer(child_id, route_id, request_id,
                                 request_data, deferred_loader);

        deferred_loader->CompleteTransfer();
      } else {
        RecordAction(UserMetricsAction("BadMessageTerminate_RDH"));
        filter_->BadMessageReceived();
      }
      return;
    }
  }

  ResourceContext* resource_context = NULL;
  net::URLRequestContext* request_context = NULL;
  filter_->GetContexts(request_data, &resource_context, &request_context);
  // http://crbug.com/90971
  CHECK(ContainsKey(active_resource_contexts_, resource_context));

  if (is_shutdown_ ||
      !ShouldServiceRequest(process_type, child_id, request_data,
                            filter_->file_system_context())) {
    AbortRequestBeforeItStarts(filter_, sync_result, request_id);
    return;
  }

  const Referrer referrer(request_data.referrer, request_data.referrer_policy);

  // Allow the observer to block/handle the request.
  if (delegate_ && !delegate_->ShouldBeginRequest(child_id,
                                                  route_id,
                                                  request_data.method,
                                                  request_data.url,
                                                  request_data.resource_type,
                                                  resource_context)) {
    AbortRequestBeforeItStarts(filter_, sync_result, request_id);
    return;
  }

  bool is_sync_load = sync_result != NULL;
  int load_flags =
      BuildLoadFlagsForRequest(request_data, child_id, is_sync_load);

  GlobalRoutingID id(child_id, route_id);
  if (!offline_policy_map_[id])
    offline_policy_map_[id] = new OfflinePolicy();
  load_flags |= offline_policy_map_[id]->GetAdditionalLoadFlags(
      load_flags, request_data.resource_type == ResourceType::MAIN_FRAME);

  // Construct the request.
  scoped_ptr<net::URLRequest> new_request;
  net::URLRequest* request;
  new_request.reset(request_context->CreateRequest(request_data.url, NULL));
  request = new_request.get();

  request->set_method(request_data.method);
  request->set_first_party_for_cookies(request_data.first_party_for_cookies);
  SetReferrerForRequest(request, referrer);

  net::HttpRequestHeaders headers;
  headers.AddHeadersFromString(request_data.headers);
  request->SetExtraRequestHeaders(headers);

  request->set_load_flags(load_flags);
  request->SetPriority(request_data.priority);

  // Resolve elements from request_body and prepare upload data.
  if (request_data.request_body.get()) {
    webkit_blob::BlobStorageContext* blob_context = NULL;
    if (filter_->blob_storage_context())
      blob_context = filter_->blob_storage_context()->context();
    request->set_upload(UploadDataStreamBuilder::Build(
        request_data.request_body.get(),
        blob_context,
        filter_->file_system_context(),
        BrowserThread::GetMessageLoopProxyForThread(BrowserThread::FILE)
            .get()));
  }

  bool allow_download = request_data.allow_download &&
      ResourceType::IsFrame(request_data.resource_type);

  // Make extra info and read footer (contains request ID).
  ResourceRequestInfoImpl* extra_info =
      new ResourceRequestInfoImpl(
          process_type,
          child_id,
          route_id,
          request_data.origin_pid,
          request_id,
          request_data.is_main_frame,
          request_data.frame_id,
          request_data.parent_is_main_frame,
          request_data.parent_frame_id,
          request_data.resource_type,
          request_data.transition_type,
          false,  // is download
          false,  // is stream
          false,  // is detachable
          allow_download,
          request_data.has_user_gesture,
          request_data.referrer_policy,
          resource_context,
          filter_->GetWeakPtr(),
          !is_sync_load);
  extra_info->AssociateWithRequest(request);  // Request takes ownership.

  if (request->url().SchemeIs(chrome::kBlobScheme)) {
    // Hang on to a reference to ensure the blob is not released prior
    // to the job being started.
    webkit_blob::BlobProtocolHandler::SetRequestedBlobDataHandle(
        request,
        filter_->blob_storage_context()->context()->
            GetBlobDataFromPublicURL(request->url()));
  }

  // Have the appcache associate its extra info with the request.
  appcache::AppCacheInterceptor::SetExtraRequestInfo(
      request, filter_->appcache_service(), child_id,
      request_data.appcache_host_id, request_data.resource_type);

  // Construct the IPC resource handler.
  scoped_ptr<ResourceHandler> handler;
  if (sync_result) {
    handler.reset(new SyncResourceHandler(request, sync_result, this));
  } else {
    handler.reset(new AsyncResourceHandler(request, this));
    if (IsDetachableResourceType(request_data.resource_type))
      extra_info->set_is_detachable(true);
  }

  // The RedirectToFileResourceHandler depends on being next in the chain.
  if (request_data.download_to_file) {
    handler.reset(
        new RedirectToFileResourceHandler(handler.Pass(), request, this));
  }

  // Install a CrossSiteResourceHandler for all main frame requests.  This will
  // let us check whether a transfer is required and pause for the unload
  // handler either if so or if a cross-process navigation is already under way.
 if (request_data.resource_type == ResourceType::MAIN_FRAME &&
     process_type == PROCESS_TYPE_RENDERER) {
    handler.reset(new CrossSiteResourceHandler(handler.Pass(), request));
  }

  // Insert a buffered event handler before the actual one.
  handler.reset(
      new BufferedResourceHandler(handler.Pass(), this, request));

  ScopedVector<ResourceThrottle> throttles;
  if (delegate_) {
    delegate_->RequestBeginning(request,
                                resource_context,
                                filter_->appcache_service(),
                                request_data.resource_type,
                                child_id,
                                route_id,
                                &throttles);
  }

  if (request->has_upload()) {
    // Block power save while uploading data.
    throttles.push_back(new PowerSaveBlockResourceThrottle());
  }

  throttles.push_back(
      scheduler_->ScheduleRequest(child_id, route_id, request).release());

  handler.reset(
      new ThrottlingResourceHandler(handler.Pass(), request, throttles.Pass()));

  BeginRequestInternal(new_request.Pass(), handler.Pass());
}

void ResourceDispatcherHostImpl::OnReleaseDownloadedFile(int request_id) {
  UnregisterDownloadedTempFile(filter_->child_id(), request_id);
}

void ResourceDispatcherHostImpl::OnDataDownloadedACK(int request_id) {
  // TODO(michaeln): maybe throttle DataDownloaded messages
}

void ResourceDispatcherHostImpl::RegisterDownloadedTempFile(
    int child_id, int request_id, ShareableFileReference* reference) {
  registered_temp_files_[child_id][request_id] = reference;
  ChildProcessSecurityPolicyImpl::GetInstance()->GrantReadFile(
      child_id, reference->path());

  // When the temp file is deleted, revoke permissions that the renderer has
  // to that file. This covers an edge case where the file is deleted and then
  // the same name is re-used for some other purpose, we don't want the old
  // renderer to still have access to it.
  //
  // We do this when the file is deleted because the renderer can take a blob
  // reference to the temp file that outlives the url loaded that it was
  // loaded with to keep the file (and permissions) alive.
  reference->AddFinalReleaseCallback(
      base::Bind(&RemoveDownloadFileFromChildSecurityPolicy,
                 child_id));
}

void ResourceDispatcherHostImpl::UnregisterDownloadedTempFile(
    int child_id, int request_id) {
  DeletableFilesMap& map = registered_temp_files_[child_id];
  DeletableFilesMap::iterator found = map.find(request_id);
  if (found == map.end())
    return;

  map.erase(found);

  // Note that we don't remove the security bits here. This will be done
  // when all file refs are deleted (see RegisterDownloadedTempFile).
}

bool ResourceDispatcherHostImpl::Send(IPC::Message* message) {
  delete message;
  return false;
}

void ResourceDispatcherHostImpl::OnUploadProgressACK(int request_id) {
  ResourceLoader* loader = GetLoader(filter_->child_id(), request_id);
  if (loader)
    loader->OnUploadProgressACK();
}

void ResourceDispatcherHostImpl::OnCancelRequest(int request_id) {
  CancelRequest(filter_->child_id(), request_id, true);
}

ResourceRequestInfoImpl* ResourceDispatcherHostImpl::CreateRequestInfo(
    int child_id,
    int route_id,
    bool download,
    ResourceContext* context) {
  return new ResourceRequestInfoImpl(
      PROCESS_TYPE_RENDERER,
      child_id,
      route_id,
      0,
      request_id_,
      false,     // is_main_frame
      -1,        // frame_id
      false,     // parent_is_main_frame
      -1,        // parent_frame_id
      ResourceType::SUB_RESOURCE,
      PAGE_TRANSITION_LINK,
      download,  // is_download
      false,     // is_stream
      false,     // is_detachable
      download,  // allow_download
      false,     // has_user_gesture
      WebKit::WebReferrerPolicyDefault,
      context,
      base::WeakPtr<ResourceMessageFilter>(),  // filter
      true);     // is_async
}

void ResourceDispatcherHostImpl::OnRenderViewHostCreated(
    int child_id,
    int route_id) {
  scheduler_->OnClientCreated(child_id, route_id);
}

void ResourceDispatcherHostImpl::OnRenderViewHostDeleted(
    int child_id,
    int route_id) {
  scheduler_->OnClientDeleted(child_id, route_id);
  CancelRequestsForRoute(child_id, route_id);
}

// This function is only used for saving feature.
void ResourceDispatcherHostImpl::BeginSaveFile(
    const GURL& url,
    const Referrer& referrer,
    int child_id,
    int route_id,
    ResourceContext* context) {
  if (is_shutdown_)
    return;

  // http://crbug.com/90971
  char url_buf[128];
  base::strlcpy(url_buf, url.spec().c_str(), arraysize(url_buf));
  base::debug::Alias(url_buf);
  CHECK(ContainsKey(active_resource_contexts_, context));

  scoped_ptr<ResourceHandler> handler(
      new SaveFileResourceHandler(child_id,
                                  route_id,
                                  url,
                                  save_file_manager_.get()));
  request_id_--;

  const net::URLRequestContext* request_context = context->GetRequestContext();
  bool known_proto =
      request_context->job_factory()->IsHandledURL(url);
  if (!known_proto) {
    // Since any URLs which have non-standard scheme have been filtered
    // by save manager(see GURL::SchemeIsStandard). This situation
    // should not happen.
    NOTREACHED();
    return;
  }

  scoped_ptr<net::URLRequest> request(
      request_context->CreateRequest(url, NULL));
  request->set_method("GET");
  SetReferrerForRequest(request.get(), referrer);

  // So far, for saving page, we need fetch content from cache, in the
  // future, maybe we can use a configuration to configure this behavior.
  request->set_load_flags(net::LOAD_PREFERRING_CACHE);

  // No need to get offline load flags for save files, but make sure
  // we have an OfflinePolicy to receive request completions.
  GlobalRoutingID id(child_id, route_id);
  if (!offline_policy_map_[id])
    offline_policy_map_[id] = new OfflinePolicy();

  // Since we're just saving some resources we need, disallow downloading.
  ResourceRequestInfoImpl* extra_info =
      CreateRequestInfo(child_id, route_id, false, context);
  extra_info->AssociateWithRequest(request.get());  // Request takes ownership.

  BeginRequestInternal(request.Pass(), handler.Pass());
}

void ResourceDispatcherHostImpl::MarkAsTransferredNavigation(
    const GlobalRequestID& id, const GURL& target_url) {
  GetLoader(id)->MarkAsTransferring(target_url);
}

void ResourceDispatcherHostImpl::ResumeDeferredNavigation(
    const GlobalRequestID& id) {
  ResourceLoader* loader = GetLoader(id);
  if (loader) {
    // The response we were meant to resume could have already been canceled.
    ResourceRequestInfoImpl* info = loader->GetRequestInfo();
    if (info->cross_site_handler())
      info->cross_site_handler()->ResumeResponse();
  }
}

// The object died, so cancel and detach all requests associated with it except
// for downloads and detachable resources, which belong to the browser process
// even if initiated via a renderer.
void ResourceDispatcherHostImpl::CancelRequestsForProcess(int child_id) {
  CancelRequestsForRoute(child_id, -1 /* cancel all */);
  registered_temp_files_.erase(child_id);
}

void ResourceDispatcherHostImpl::CancelRequestsForRoute(int child_id,
                                                        int route_id) {
  // Since pending_requests_ is a map, we first build up a list of all of the
  // matching requests to be cancelled, and then we cancel them.  Since there
  // may be more than one request to cancel, we cannot simply hold onto the map
  // iterators found in the first loop.

  // Find the global ID of all matching elements.
  bool any_requests_transferring = false;
  std::vector<GlobalRequestID> matching_requests;
  for (LoaderMap::const_iterator i = pending_loaders_.begin();
       i != pending_loaders_.end(); ++i) {
    if (i->first.child_id != child_id)
      continue;

    ResourceRequestInfoImpl* info = i->second->GetRequestInfo();

    GlobalRequestID id(child_id, i->first.request_id);
    DCHECK(id == i->first);
    // Don't cancel navigations that are expected to live beyond this process.
    if (IsTransferredNavigation(id))
      any_requests_transferring = true;

    if (info->is_detachable()) {
      i->second->Detach();
    } else if (!info->is_download() && !info->is_stream() &&
               !IsTransferredNavigation(id) &&
               (route_id == -1 || route_id == info->GetRouteID())) {
      matching_requests.push_back(id);
    }
  }

  // Remove matches.
  for (size_t i = 0; i < matching_requests.size(); ++i) {
    LoaderMap::iterator iter = pending_loaders_.find(matching_requests[i]);
    // Although every matching request was in pending_requests_ when we built
    // matching_requests, it is normal for a matching request to be not found
    // in pending_requests_ after we have removed some matching requests from
    // pending_requests_.  For example, deleting a net::URLRequest that has
    // exclusive (write) access to an HTTP cache entry may unblock another
    // net::URLRequest that needs exclusive access to the same cache entry, and
    // that net::URLRequest may complete and remove itself from
    // pending_requests_. So we need to check that iter is not equal to
    // pending_requests_.end().
    if (iter != pending_loaders_.end())
      RemovePendingLoader(iter);
  }

  // Don't clear the blocked loaders or offline policy maps if any of the
  // requests in route_id are being transferred to a new process, since those
  // maps will be updated with the new route_id after the transfer.  Otherwise
  // we will lose track of this info when the old route goes away, before the
  // new one is created.
  if (any_requests_transferring)
    return;

  // Now deal with blocked requests if any.
  if (route_id != -1) {
    if (blocked_loaders_map_.find(GlobalRoutingID(child_id, route_id)) !=
        blocked_loaders_map_.end()) {
      CancelBlockedRequestsForRoute(child_id, route_id);
    }
  } else {
    // We have to do all render views for the process |child_id|.
    // Note that we have to do this in 2 passes as we cannot call
    // CancelBlockedRequestsForRoute while iterating over
    // blocked_loaders_map_, as it modifies it.
    std::set<int> route_ids;
    for (BlockedLoadersMap::const_iterator iter = blocked_loaders_map_.begin();
         iter != blocked_loaders_map_.end(); ++iter) {
      if (iter->first.child_id == child_id)
        route_ids.insert(iter->first.route_id);
    }
    for (std::set<int>::const_iterator iter = route_ids.begin();
        iter != route_ids.end(); ++iter) {
      CancelBlockedRequestsForRoute(child_id, *iter);
    }
  }

  // Cleanup the offline state for the route.
  if (-1 != route_id) {
    OfflineMap::iterator it = offline_policy_map_.find(
        GlobalRoutingID(child_id, route_id));
    if (offline_policy_map_.end() != it) {
      delete it->second;
      offline_policy_map_.erase(it);
    }
  } else {
    for (OfflineMap::iterator it = offline_policy_map_.begin();
         offline_policy_map_.end() != it;) {
      // Increment iterator so deletion doesn't invalidate it.
      OfflineMap::iterator current_it = it++;

      if (child_id == current_it->first.child_id) {
        delete current_it->second;
        offline_policy_map_.erase(current_it);
      }
    }
  }
}

// Cancels the request and removes it from the list.
void ResourceDispatcherHostImpl::RemovePendingRequest(int child_id,
                                                      int request_id) {
  LoaderMap::iterator i = pending_loaders_.find(
      GlobalRequestID(child_id, request_id));
  if (i == pending_loaders_.end()) {
    NOTREACHED() << "Trying to remove a request that's not here";
    return;
  }
  RemovePendingLoader(i);
}

void ResourceDispatcherHostImpl::RemovePendingLoader(
    const LoaderMap::iterator& iter) {
  ResourceRequestInfoImpl* info = iter->second->GetRequestInfo();

  // Remove the memory credit that we added when pushing the request onto
  // the pending list.
  IncrementOutstandingRequestsMemory(-1, *info);

  pending_loaders_.erase(iter);

  // If we have no more pending requests, then stop the load state monitor
  if (pending_loaders_.empty() && update_load_states_timer_)
    update_load_states_timer_->Stop();
}

void ResourceDispatcherHostImpl::CancelRequest(int child_id,
                                               int request_id,
                                               bool from_renderer) {
  if (from_renderer) {
    // When the old renderer dies, it sends a message to us to cancel its
    // requests.
    if (IsTransferredNavigation(GlobalRequestID(child_id, request_id)))
      return;
  }

  ResourceLoader* loader = GetLoader(child_id, request_id);
  if (!loader) {
    // We probably want to remove this warning eventually, but I wanted to be
    // able to notice when this happens during initial development since it
    // should be rare and may indicate a bug.
    DVLOG(1) << "Canceling a request that wasn't found";
    return;
  }

  loader->CancelRequest(from_renderer);
}

ResourceDispatcherHostImpl::OustandingRequestsStats
ResourceDispatcherHostImpl::GetOutstandingRequestsStats(
    const ResourceRequestInfoImpl& info) {
  OutstandingRequestsStatsMap::iterator entry =
      outstanding_requests_stats_map_.find(info.GetChildID());
  OustandingRequestsStats stats = { 0, 0 };
  if (entry != outstanding_requests_stats_map_.end())
    stats = entry->second;
  return stats;
}

void ResourceDispatcherHostImpl::UpdateOutstandingRequestsStats(
    const ResourceRequestInfoImpl& info,
    const OustandingRequestsStats& stats) {
  if (stats.memory_cost == 0 && stats.num_requests == 0)
    outstanding_requests_stats_map_.erase(info.GetChildID());
  else
    outstanding_requests_stats_map_[info.GetChildID()] = stats;
}

ResourceDispatcherHostImpl::OustandingRequestsStats
ResourceDispatcherHostImpl::IncrementOutstandingRequestsMemory(
    int count,
    const ResourceRequestInfoImpl& info) {
  DCHECK_EQ(1, abs(count));

  // Retrieve the previous value (defaulting to 0 if not found).
  OustandingRequestsStats stats = GetOutstandingRequestsStats(info);

  // Insert/update the total; delete entries when their count reaches 0.
  stats.memory_cost += count * info.memory_cost();
  DCHECK_GE(stats.memory_cost, 0);
  UpdateOutstandingRequestsStats(info, stats);

  return stats;
}

ResourceDispatcherHostImpl::OustandingRequestsStats
ResourceDispatcherHostImpl::IncrementOutstandingRequestsCount(
    int count,
    const ResourceRequestInfoImpl& info) {
  DCHECK_EQ(1, abs(count));
  num_in_flight_requests_ += count;

  OustandingRequestsStats stats = GetOutstandingRequestsStats(info);
  stats.num_requests += count;
  DCHECK_GE(stats.num_requests, 0);
  UpdateOutstandingRequestsStats(info, stats);

  return stats;
}

bool ResourceDispatcherHostImpl::HasSufficientResourcesForRequest(
    const net::URLRequest* request_) {
  const ResourceRequestInfoImpl* info =
      ResourceRequestInfoImpl::ForRequest(request_);
  OustandingRequestsStats stats = IncrementOutstandingRequestsCount(1, *info);

  if (stats.num_requests > max_num_in_flight_requests_per_process_)
    return false;
  if (num_in_flight_requests_ > max_num_in_flight_requests_)
    return false;

  return true;
}

void ResourceDispatcherHostImpl::FinishedWithResourcesForRequest(
    const net::URLRequest* request_) {
  const ResourceRequestInfoImpl* info =
      ResourceRequestInfoImpl::ForRequest(request_);
  IncrementOutstandingRequestsCount(-1, *info);
}

// static
int ResourceDispatcherHostImpl::CalculateApproximateMemoryCost(
    net::URLRequest* request) {
  // The following fields should be a minor size contribution (experimentally
  // on the order of 100). However since they are variable length, it could
  // in theory be a sizeable contribution.
  int strings_cost = request->extra_request_headers().ToString().size() +
                     request->original_url().spec().size() +
                     request->referrer().size() +
                     request->method().size();

  // Note that this expression will typically be dominated by:
  // |kAvgBytesPerOutstandingRequest|.
  return kAvgBytesPerOutstandingRequest + strings_cost;
}

void ResourceDispatcherHostImpl::BeginRequestInternal(
    scoped_ptr<net::URLRequest> request,
    scoped_ptr<ResourceHandler> handler) {
  DCHECK(!request->is_pending());
  ResourceRequestInfoImpl* info =
      ResourceRequestInfoImpl::ForRequest(request.get());

  if ((TimeTicks::Now() - last_user_gesture_time_) <
      TimeDelta::FromMilliseconds(kUserGestureWindowMs)) {
    request->set_load_flags(
        request->load_flags() | net::LOAD_MAYBE_USER_GESTURE);
  }

  // Add the memory estimate that starting this request will consume.
  info->set_memory_cost(CalculateApproximateMemoryCost(request.get()));

  // If enqueing/starting this request will exceed our per-process memory
  // bound, abort it right away.
  OustandingRequestsStats stats = IncrementOutstandingRequestsMemory(1, *info);
  if (stats.memory_cost > max_outstanding_requests_cost_per_process_) {
    // We call "CancelWithError()" as a way of setting the net::URLRequest's
    // status -- it has no effect beyond this, since the request hasn't started.
    request->CancelWithError(net::ERR_INSUFFICIENT_RESOURCES);

    if (!handler->OnResponseCompleted(info->GetRequestID(), request->status(),
                                      std::string())) {
      // TODO(darin): The handler is not ready for us to kill the request. Oops!
      NOTREACHED();
    }

    IncrementOutstandingRequestsMemory(-1, *info);

    // A ResourceHandler must not outlive its associated URLRequest.
    handler.reset();
    return;
  }

  linked_ptr<ResourceLoader> loader(
      new ResourceLoader(request.Pass(), handler.Pass(), this));

  GlobalRoutingID id(info->GetGlobalRoutingID());
  BlockedLoadersMap::const_iterator iter = blocked_loaders_map_.find(id);
  if (iter != blocked_loaders_map_.end()) {
    // The request should be blocked.
    iter->second->push_back(loader);
    return;
  }

  StartLoading(info, loader);
}

void ResourceDispatcherHostImpl::StartLoading(
    ResourceRequestInfoImpl* info,
    const linked_ptr<ResourceLoader>& loader) {
  pending_loaders_[info->GetGlobalRequestID()] = loader;

  loader->StartRequest();
}

void ResourceDispatcherHostImpl::OnUserGesture(WebContentsImpl* contents) {
  last_user_gesture_time_ = TimeTicks::Now();
}

net::URLRequest* ResourceDispatcherHostImpl::GetURLRequest(
    const GlobalRequestID& id) {
  ResourceLoader* loader = GetLoader(id);
  if (!loader)
    return NULL;

  return loader->request();
}

namespace {

// This function attempts to return the "more interesting" load state of |a|
// and |b|.  We don't have temporal information about these load states
// (meaning we don't know when we transitioned into these states), so we just
// rank them according to how "interesting" the states are.
//
// We take advantage of the fact that the load states are an enumeration listed
// in the order in which they occur during the lifetime of a request, so we can
// regard states with larger numeric values as being further along toward
// completion.  We regard those states as more interesting to report since they
// represent progress.
//
// For example, by this measure "tranferring data" is a more interesting state
// than "resolving host" because when we are transferring data we are actually
// doing something that corresponds to changes that the user might observe,
// whereas waiting for a host name to resolve implies being stuck.
//
const net::LoadStateWithParam& MoreInterestingLoadState(
    const net::LoadStateWithParam& a, const net::LoadStateWithParam& b) {
  return (a.state < b.state) ? b : a;
}

// Carries information about a load state change.
struct LoadInfo {
  GURL url;
  net::LoadStateWithParam load_state;
  uint64 upload_position;
  uint64 upload_size;
};

// Map from ProcessID+RouteID pair to LoadState
typedef std::map<GlobalRoutingID, LoadInfo> LoadInfoMap;

// Used to marshal calls to LoadStateChanged from the IO to UI threads.  We do
// them all as a single callback to avoid spamming the UI thread.
void LoadInfoUpdateCallback(const LoadInfoMap& info_map) {
  LoadInfoMap::const_iterator i;
  for (i = info_map.begin(); i != info_map.end(); ++i) {
    RenderViewHostImpl* view =
        RenderViewHostImpl::FromID(i->first.child_id, i->first.route_id);
    if (view)  // The view could be gone at this point.
      view->LoadStateChanged(i->second.url, i->second.load_state,
                             i->second.upload_position,
                             i->second.upload_size);
  }
}

}  // namespace

void ResourceDispatcherHostImpl::UpdateLoadStates() {
  // Populate this map with load state changes, and then send them on to the UI
  // thread where they can be passed along to the respective RVHs.
  LoadInfoMap info_map;

  LoaderMap::const_iterator i;

  // Determine the largest upload size of all requests
  // in each View (good chance it's zero).
  std::map<GlobalRoutingID, uint64> largest_upload_size;
  for (i = pending_loaders_.begin(); i != pending_loaders_.end(); ++i) {
    net::URLRequest* request = i->second->request();
    ResourceRequestInfoImpl* info = i->second->GetRequestInfo();
    uint64 upload_size = request->GetUploadProgress().size();
    if (request->GetLoadState().state != net::LOAD_STATE_SENDING_REQUEST)
      upload_size = 0;
    GlobalRoutingID id(info->GetGlobalRoutingID());
    if (upload_size && largest_upload_size[id] < upload_size)
      largest_upload_size[id] = upload_size;
  }

  for (i = pending_loaders_.begin(); i != pending_loaders_.end(); ++i) {
    net::URLRequest* request = i->second->request();
    ResourceRequestInfoImpl* info = i->second->GetRequestInfo();
    net::LoadStateWithParam load_state = request->GetLoadState();
    net::UploadProgress progress = request->GetUploadProgress();

    // We also poll for upload progress on this timer and send upload
    // progress ipc messages to the plugin process.
    i->second->ReportUploadProgress();

    GlobalRoutingID id(info->GetGlobalRoutingID());

    // If a request is uploading data, ignore all other requests so that the
    // upload progress takes priority for being shown in the status bar.
    if (largest_upload_size.find(id) != largest_upload_size.end() &&
        progress.size() < largest_upload_size[id])
      continue;

    net::LoadStateWithParam to_insert = load_state;
    LoadInfoMap::iterator existing = info_map.find(id);
    if (existing != info_map.end()) {
      to_insert =
          MoreInterestingLoadState(existing->second.load_state, load_state);
      if (to_insert.state == existing->second.load_state.state)
        continue;
    }
    LoadInfo& load_info = info_map[id];
    load_info.url = request->url();
    load_info.load_state = to_insert;
    load_info.upload_size = progress.size();
    load_info.upload_position = progress.position();
  }

  if (info_map.empty())
    return;

  BrowserThread::PostTask(
      BrowserThread::UI, FROM_HERE,
      base::Bind(&LoadInfoUpdateCallback, info_map));
}

void ResourceDispatcherHostImpl::BlockRequestsForRoute(int child_id,
                                                       int route_id) {
  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
  GlobalRoutingID key(child_id, route_id);
  DCHECK(blocked_loaders_map_.find(key) == blocked_loaders_map_.end()) <<
      "BlockRequestsForRoute called  multiple time for the same RVH";
  blocked_loaders_map_[key] = new BlockedLoadersList();
}

void ResourceDispatcherHostImpl::ResumeBlockedRequestsForRoute(int child_id,
                                                               int route_id) {
  ProcessBlockedRequestsForRoute(child_id, route_id, false);
}

void ResourceDispatcherHostImpl::CancelBlockedRequestsForRoute(int child_id,
                                                               int route_id) {
  ProcessBlockedRequestsForRoute(child_id, route_id, true);
}

void ResourceDispatcherHostImpl::ProcessBlockedRequestsForRoute(
    int child_id,
    int route_id,
    bool cancel_requests) {
  BlockedLoadersMap::iterator iter = blocked_loaders_map_.find(
      GlobalRoutingID(child_id, route_id));
  if (iter == blocked_loaders_map_.end()) {
    // It's possible to reach here if the renderer crashed while an interstitial
    // page was showing.
    return;
  }

  BlockedLoadersList* loaders = iter->second;

  // Removing the vector from the map unblocks any subsequent requests.
  blocked_loaders_map_.erase(iter);

  for (BlockedLoadersList::iterator loaders_iter = loaders->begin();
       loaders_iter != loaders->end(); ++loaders_iter) {
    linked_ptr<ResourceLoader> loader = *loaders_iter;
    ResourceRequestInfoImpl* info = loader->GetRequestInfo();
    if (cancel_requests) {
      IncrementOutstandingRequestsMemory(-1, *info);
    } else {
      StartLoading(info, loader);
    }
  }

  delete loaders;
}

ResourceDispatcherHostImpl::HttpAuthRelationType
ResourceDispatcherHostImpl::HttpAuthRelationTypeOf(
    const GURL& request_url,
    const GURL& first_party) {
  if (!first_party.is_valid())
    return HTTP_AUTH_RELATION_TOP;

  if (net::registry_controlled_domains::SameDomainOrHost(
          first_party, request_url,
          net::registry_controlled_domains::EXCLUDE_PRIVATE_REGISTRIES))
    return HTTP_AUTH_RELATION_SAME_DOMAIN;

  if (allow_cross_origin_auth_prompt())
    return HTTP_AUTH_RELATION_ALLOWED_CROSS;

  return HTTP_AUTH_RELATION_BLOCKED_CROSS;
}

bool ResourceDispatcherHostImpl::allow_cross_origin_auth_prompt() {
  return allow_cross_origin_auth_prompt_;
}

bool ResourceDispatcherHostImpl::IsTransferredNavigation(
    const GlobalRequestID& id) const {
  ResourceLoader* loader = GetLoader(id);
  return loader ? loader->is_transferring() : false;
}

ResourceLoader* ResourceDispatcherHostImpl::GetLoader(
    const GlobalRequestID& id) const {
  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));

  LoaderMap::const_iterator i = pending_loaders_.find(id);
  if (i == pending_loaders_.end())
    return NULL;

  return i->second.get();
}

ResourceLoader* ResourceDispatcherHostImpl::GetLoader(int child_id,
                                                      int request_id) const {
  return GetLoader(GlobalRequestID(child_id, request_id));
}

void ResourceDispatcherHostImpl::RegisterResourceMessageDelegate(
    const GlobalRequestID& id, ResourceMessageDelegate* delegate) {
  DelegateMap::iterator it = delegate_map_.find(id);
  if (it == delegate_map_.end()) {
    it = delegate_map_.insert(
        std::make_pair(id, new ObserverList<ResourceMessageDelegate>)).first;
  }
  it->second->AddObserver(delegate);
}

void ResourceDispatcherHostImpl::UnregisterResourceMessageDelegate(
    const GlobalRequestID& id, ResourceMessageDelegate* delegate) {
  DCHECK(ContainsKey(delegate_map_, id));
  DelegateMap::iterator it = delegate_map_.find(id);
  DCHECK(it->second->HasObserver(delegate));
  it->second->RemoveObserver(delegate);
  if (!it->second->might_have_observers()) {
    delete it->second;
    delegate_map_.erase(it);
  }
}

int ResourceDispatcherHostImpl::BuildLoadFlagsForRequest(
    const ResourceHostMsg_Request& request_data,
    int child_id,
    bool is_sync_load) {
  int load_flags = request_data.load_flags;

  // Although EV status is irrelevant to sub-frames and sub-resources, we have
  // to perform EV certificate verification on all resources because an HTTP
  // keep-alive connection created to load a sub-frame or a sub-resource could
  // be reused to load a main frame.
  load_flags |= net::LOAD_VERIFY_EV_CERT;
  if (request_data.resource_type == ResourceType::MAIN_FRAME) {
    load_flags |= net::LOAD_MAIN_FRAME;
  } else if (request_data.resource_type == ResourceType::SUB_FRAME) {
    load_flags |= net::LOAD_SUB_FRAME;
  } else if (request_data.resource_type == ResourceType::PREFETCH) {
    load_flags |= (net::LOAD_PREFETCH | net::LOAD_DO_NOT_PROMPT_FOR_LOGIN);
  } else if (request_data.resource_type == ResourceType::FAVICON) {
    load_flags |= net::LOAD_DO_NOT_PROMPT_FOR_LOGIN;
  } else if (request_data.resource_type == ResourceType::IMAGE) {
    // Prevent third-party image content from prompting for login, as this
    // is often a scam to extract credentials for another domain from the user.
    // Only block image loads, as the attack applies largely to the "src"
    // property of the <img> tag. It is common for web properties to allow
    // untrusted values for <img src>; this is considered a fair thing for an
    // HTML sanitizer to do. Conversely, any HTML sanitizer that didn't
    // filter sources for <script>, <link>, <embed>, <object>, <iframe> tags
    // would be considered vulnerable in and of itself.
    HttpAuthRelationType relation_type = HttpAuthRelationTypeOf(
        request_data.url, request_data.first_party_for_cookies);
    if (relation_type == HTTP_AUTH_RELATION_BLOCKED_CROSS) {
      load_flags |= (net::LOAD_DO_NOT_USE_EMBEDDED_IDENTITY |
                     net::LOAD_DO_NOT_PROMPT_FOR_LOGIN);
    }
  }

  if (is_sync_load)
    load_flags |= net::LOAD_IGNORE_LIMITS;

  ChildProcessSecurityPolicyImpl* policy =
      ChildProcessSecurityPolicyImpl::GetInstance();
  if (!policy->CanSendCookiesForOrigin(child_id, request_data.url)) {
    load_flags |= (net::LOAD_DO_NOT_SEND_COOKIES |
                   net::LOAD_DO_NOT_SEND_AUTH_DATA |
                   net::LOAD_DO_NOT_SAVE_COOKIES);
  }

  // Raw headers are sensitive, as they include Cookie/Set-Cookie, so only
  // allow requesting them if requester has ReadRawCookies permission.
  if ((load_flags & net::LOAD_REPORT_RAW_HEADERS)
      && !policy->CanReadRawCookies(child_id)) {
    VLOG(1) << "Denied unauthorized request for raw headers";
    load_flags &= ~net::LOAD_REPORT_RAW_HEADERS;
  }

  return load_flags;
}

}  // namespace content