chrome/browser/media/media_capture_devices_dispatcher.cc

// 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.

#include "chrome/browser/media/media_capture_devices_dispatcher.h"

#include "apps/app_window.h"
#include "apps/app_window_registry.h"
#include "base/command_line.h"
#include "base/logging.h"
#include "base/metrics/field_trial.h"
#include "base/prefs/pref_service.h"
#include "base/prefs/scoped_user_pref_update.h"
#include "base/sha1.h"
#include "base/strings/string_number_conversions.h"
#include "base/strings/string_util.h"
#include "base/strings/utf_string_conversions.h"
#include "chrome/browser/extensions/api/tab_capture/tab_capture_registry.h"
#include "chrome/browser/media/desktop_streams_registry.h"
#include "chrome/browser/media/media_stream_capture_indicator.h"
#include "chrome/browser/media/media_stream_infobar_delegate.h"
#include "chrome/browser/profiles/profile.h"
#include "chrome/browser/ui/browser.h"
#include "chrome/browser/ui/browser_finder.h"
#include "chrome/browser/ui/browser_window.h"
#include "chrome/browser/ui/screen_capture_notification_ui.h"
#include "chrome/browser/ui/simple_message_box.h"
#include "chrome/browser/ui/website_settings/permission_bubble_manager.h"
#include "chrome/common/chrome_switches.h"
#include "chrome/common/chrome_version_info.h"
#include "chrome/common/pref_names.h"
#include "components/pref_registry/pref_registry_syncable.h"
#include "content/public/browser/browser_thread.h"
#include "content/public/browser/desktop_media_id.h"
#include "content/public/browser/media_capture_devices.h"
#include "content/public/browser/notification_service.h"
#include "content/public/browser/notification_source.h"
#include "content/public/browser/notification_types.h"
#include "content/public/browser/render_frame_host.h"
#include "content/public/browser/web_contents.h"
#include "content/public/common/media_stream_request.h"
#include "extensions/common/constants.h"
#include "extensions/common/extension.h"
#include "extensions/common/permissions/permissions_data.h"
#include "grit/generated_resources.h"
#include "media/audio/audio_manager_base.h"
#include "media/base/media_switches.h"
#include "net/base/net_util.h"
#include "third_party/webrtc/modules/desktop_capture/desktop_capture_types.h"
#include "ui/base/l10n/l10n_util.h"

#if defined(OS_CHROMEOS)
#include "ash/shell.h"
#endif  // defined(OS_CHROMEOS)

// Only do audio stream monitoring for platforms that use it for the tab media
// indicator UI or the OOM killer.
#if !defined(OS_ANDROID) && !defined(OS_IOS)
#define AUDIO_STREAM_MONITORING
#include "chrome/browser/media/audio_stream_monitor.h"
#endif  // !defined(OS_ANDROID) && !defined(OS_IOS)

using content::BrowserThread;
using content::MediaCaptureDevices;
using content::MediaStreamDevices;

namespace {

// A finch experiment to enable the permission bubble for media requests only.
bool MediaStreamPermissionBubbleExperimentEnabled() {
  const std::string group =
      base::FieldTrialList::FindFullName("MediaStreamPermissionBubble");
  if (group == "enabled")
    return true;

  return false;
}

// Finds a device in |devices| that has |device_id|, or NULL if not found.
const content::MediaStreamDevice* FindDeviceWithId(
    const content::MediaStreamDevices& devices,
    const std::string& device_id) {
  content::MediaStreamDevices::const_iterator iter = devices.begin();
  for (; iter != devices.end(); ++iter) {
    if (iter->id == device_id) {
      return &(*iter);
    }
  }
  return NULL;
}

// This is a short-term solution to grant camera and/or microphone access to
// extensions:
// 1. Virtual keyboard extension.
// 2. Google Voice Search Hotword extension.
// 3. Flutter gesture recognition extension.
// 4. TODO(smus): Airbender experiment 1.
// 5. TODO(smus): Airbender experiment 2.
// Once http://crbug.com/292856 is fixed, remove this whitelist.
bool IsMediaRequestWhitelistedForExtension(
    const extensions::Extension* extension) {
  return extension->id() == "mppnpdlheglhdfmldimlhpnegondlapf" ||
      extension->id() == "bepbmhgboaologfdajaanbcjmnhjmhfn" ||
      extension->id() == "jokbpnebhdcladagohdnfgjcpejggllo" ||
      extension->id() == "clffjmdilanldobdnedchkdbofoimcgb" ||
      extension->id() == "nnckehldicaciogcbchegobnafnjkcne";
}

bool IsBuiltInExtension(const GURL& origin) {
  return
      // Feedback Extension.
      origin.spec() == "chrome-extension://gfdkimpbcpahaombhbimeihdjnejgicl/";
}

// Returns true of the security origin is associated with casting.
bool IsOriginForCasting(const GURL& origin) {
#if defined(OFFICIAL_BUILD)
  // Whitelisted tab casting extensions.
  return
      // Dev
      origin.spec() == "chrome-extension://enhhojjnijigcajfphajepfemndkmdlo/" ||
      // Canary
      origin.spec() == "chrome-extension://hfaagokkkhdbgiakmmlclaapfelnkoah/" ||
      // Beta (internal)
      origin.spec() == "chrome-extension://fmfcbgogabcbclcofgocippekhfcmgfj/" ||
      // Google Cast Beta
      origin.spec() == "chrome-extension://dliochdbjfkdbacpmhlcpmleaejidimm/" ||
      // Google Cast Stable
      origin.spec() == "chrome-extension://boadgeojelhgndaghljhdicfkmllpafd/";
#else
  return false;
#endif
}

// Helper to get title of the calling application shown in the screen capture
// notification.
base::string16 GetApplicationTitle(content::WebContents* web_contents,
                                   const extensions::Extension* extension) {
  // Use extension name as title for extensions and host/origin for drive-by
  // web.
  std::string title;
  if (extension) {
    title = extension->name();
  } else {
    GURL url = web_contents->GetURL();
    title = url.SchemeIsSecure() ? net::GetHostAndOptionalPort(url)
                                 : url.GetOrigin().spec();
  }
  return base::UTF8ToUTF16(title);
}

// Helper to get list of media stream devices for desktop capture in |devices|.
// Registers to display notification if |display_notification| is true.
// Returns an instance of MediaStreamUI to be passed to content layer.
scoped_ptr<content::MediaStreamUI> GetDevicesForDesktopCapture(
    content::MediaStreamDevices& devices,
    content::DesktopMediaID media_id,
    bool capture_audio,
    bool display_notification,
    const base::string16& application_title,
    const base::string16& registered_extension_name) {
  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
  scoped_ptr<content::MediaStreamUI> ui;

  // Add selected desktop source to the list.
  devices.push_back(content::MediaStreamDevice(
      content::MEDIA_DESKTOP_VIDEO_CAPTURE, media_id.ToString(), "Screen"));
  if (capture_audio) {
    // Use the special loopback device ID for system audio capture.
    devices.push_back(content::MediaStreamDevice(
        content::MEDIA_LOOPBACK_AUDIO_CAPTURE,
        media::AudioManagerBase::kLoopbackInputDeviceId, "System Audio"));
  }

  // If required, register to display the notification for stream capture.
  if (display_notification) {
    if (application_title == registered_extension_name) {
      ui = ScreenCaptureNotificationUI::Create(l10n_util::GetStringFUTF16(
          IDS_MEDIA_SCREEN_CAPTURE_NOTIFICATION_TEXT,
          application_title));
    } else {
      ui = ScreenCaptureNotificationUI::Create(l10n_util::GetStringFUTF16(
          IDS_MEDIA_SCREEN_CAPTURE_NOTIFICATION_TEXT_DELEGATED,
          registered_extension_name,
          application_title));
    }
  }

  return ui.Pass();
}

#if defined(AUDIO_STREAM_MONITORING)

AudioStreamMonitor* AudioStreamMonitorFromRenderFrame(
    int render_process_id,
    int render_frame_id) {
  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
  content::WebContents* const web_contents =
      content::WebContents::FromRenderFrameHost(
          content::RenderFrameHost::FromID(render_process_id, render_frame_id));
  if (!web_contents)
    return NULL;
  return AudioStreamMonitor::FromWebContents(web_contents);
}

void StartAudioStreamMonitoringOnUIThread(
    int render_process_id,
    int render_frame_id,
    int stream_id,
    const AudioStreamMonitor::ReadPowerAndClipCallback& read_power_callback) {
  AudioStreamMonitor* const audio_stream_monitor =
      AudioStreamMonitorFromRenderFrame(render_process_id, render_frame_id);
  if (audio_stream_monitor)
    audio_stream_monitor->StartMonitoringStream(stream_id, read_power_callback);
}

void StopAudioStreamMonitoringOnUIThread(
    int render_process_id,
    int render_frame_id,
    int stream_id) {
  AudioStreamMonitor* const audio_stream_monitor =
      AudioStreamMonitorFromRenderFrame(render_process_id, render_frame_id);
  if (audio_stream_monitor)
    audio_stream_monitor->StopMonitoringStream(stream_id);
}

#endif  // defined(AUDIO_STREAM_MONITORING)

#if !defined(OS_ANDROID)
// Find browser or app window from a given |web_contents|.
gfx::NativeWindow FindParentWindowForWebContents(
    content::WebContents* web_contents) {
  Browser* browser = chrome::FindBrowserWithWebContents(web_contents);
  if (browser && browser->window())
    return browser->window()->GetNativeWindow();

  const apps::AppWindowRegistry::AppWindowList& window_list =
      apps::AppWindowRegistry::Get(
          web_contents->GetBrowserContext())->app_windows();
  for (apps::AppWindowRegistry::AppWindowList::const_iterator iter =
           window_list.begin();
       iter != window_list.end(); ++iter) {
    if ((*iter)->web_contents() == web_contents)
      return (*iter)->GetNativeWindow();
  }

  return NULL;
}
#endif

}  // namespace

MediaCaptureDevicesDispatcher::PendingAccessRequest::PendingAccessRequest(
    const content::MediaStreamRequest& request,
    const content::MediaResponseCallback& callback)
    : request(request),
      callback(callback) {
}

MediaCaptureDevicesDispatcher::PendingAccessRequest::~PendingAccessRequest() {}

MediaCaptureDevicesDispatcher* MediaCaptureDevicesDispatcher::GetInstance() {
  return Singleton<MediaCaptureDevicesDispatcher>::get();
}

MediaCaptureDevicesDispatcher::MediaCaptureDevicesDispatcher()
    : is_device_enumeration_disabled_(false),
      media_stream_capture_indicator_(new MediaStreamCaptureIndicator()) {
  // MediaCaptureDevicesDispatcher is a singleton. It should be created on
  // UI thread. Otherwise, it will not receive
  // content::NOTIFICATION_WEB_CONTENTS_DESTROYED, and that will result in
  // possible use after free.
  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
  notifications_registrar_.Add(
      this, content::NOTIFICATION_WEB_CONTENTS_DESTROYED,
      content::NotificationService::AllSources());

  // AVFoundation is used for video/audio device monitoring and video capture in
  // Mac. Experimentally, connect it in Canary and Unkown (developer builds).
#if defined(OS_MACOSX)
  chrome::VersionInfo::Channel channel = chrome::VersionInfo::GetChannel();
  if (channel == chrome::VersionInfo::CHANNEL_CANARY ||
      channel == chrome::VersionInfo::CHANNEL_UNKNOWN) {
    CommandLine::ForCurrentProcess()->AppendSwitch(
        switches::kEnableAVFoundation);
  }
#endif
}

MediaCaptureDevicesDispatcher::~MediaCaptureDevicesDispatcher() {}

void MediaCaptureDevicesDispatcher::RegisterProfilePrefs(
    user_prefs::PrefRegistrySyncable* registry) {
  registry->RegisterStringPref(
      prefs::kDefaultAudioCaptureDevice,
      std::string(),
      user_prefs::PrefRegistrySyncable::UNSYNCABLE_PREF);
  registry->RegisterStringPref(
      prefs::kDefaultVideoCaptureDevice,
      std::string(),
      user_prefs::PrefRegistrySyncable::UNSYNCABLE_PREF);
}

void MediaCaptureDevicesDispatcher::AddObserver(Observer* observer) {
  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
  if (!observers_.HasObserver(observer))
    observers_.AddObserver(observer);
}

void MediaCaptureDevicesDispatcher::RemoveObserver(Observer* observer) {
  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
  observers_.RemoveObserver(observer);
}

const MediaStreamDevices&
MediaCaptureDevicesDispatcher::GetAudioCaptureDevices() {
  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
  if (is_device_enumeration_disabled_ || !test_audio_devices_.empty())
    return test_audio_devices_;

  return MediaCaptureDevices::GetInstance()->GetAudioCaptureDevices();
}

const MediaStreamDevices&
MediaCaptureDevicesDispatcher::GetVideoCaptureDevices() {
  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
  if (is_device_enumeration_disabled_ || !test_video_devices_.empty())
    return test_video_devices_;

  return MediaCaptureDevices::GetInstance()->GetVideoCaptureDevices();
}

void MediaCaptureDevicesDispatcher::Observe(
    int type,
    const content::NotificationSource& source,
    const content::NotificationDetails& details) {
  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
  if (type == content::NOTIFICATION_WEB_CONTENTS_DESTROYED) {
    content::WebContents* web_contents =
        content::Source<content::WebContents>(source).ptr();
    pending_requests_.erase(web_contents);
  }
}

void MediaCaptureDevicesDispatcher::ProcessMediaAccessRequest(
    content::WebContents* web_contents,
    const content::MediaStreamRequest& request,
    const content::MediaResponseCallback& callback,
    const extensions::Extension* extension) {
  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));

  if (request.video_type == content::MEDIA_DESKTOP_VIDEO_CAPTURE ||
      request.audio_type == content::MEDIA_LOOPBACK_AUDIO_CAPTURE) {
    ProcessDesktopCaptureAccessRequest(
        web_contents, request, callback, extension);
  } else if (request.video_type == content::MEDIA_TAB_VIDEO_CAPTURE ||
             request.audio_type == content::MEDIA_TAB_AUDIO_CAPTURE) {
    ProcessTabCaptureAccessRequest(
        web_contents, request, callback, extension);
  } else if (extension && (extension->is_platform_app() ||
                           IsMediaRequestWhitelistedForExtension(extension))) {
    // For extensions access is approved based on extension permissions.
    ProcessMediaAccessRequestFromPlatformAppOrExtension(
        web_contents, request, callback, extension);
  } else {
    ProcessRegularMediaAccessRequest(web_contents, request, callback);
  }
}

void MediaCaptureDevicesDispatcher::ProcessDesktopCaptureAccessRequest(
    content::WebContents* web_contents,
    const content::MediaStreamRequest& request,
    const content::MediaResponseCallback& callback,
    const extensions::Extension* extension) {
  content::MediaStreamDevices devices;
  scoped_ptr<content::MediaStreamUI> ui;

  if (request.video_type != content::MEDIA_DESKTOP_VIDEO_CAPTURE) {
    callback.Run(devices, content::MEDIA_DEVICE_INVALID_STATE, ui.Pass());
    return;
  }

  // If the device id wasn't specified then this is a screen capture request
  // (i.e. chooseDesktopMedia() API wasn't used to generate device id).
  if (request.requested_video_device_id.empty()) {
    ProcessScreenCaptureAccessRequest(
        web_contents, request, callback, extension);
    return;
  }

  // The extension name that the stream is registered with.
  std::string original_extension_name;
  // Resolve DesktopMediaID for the specified device id.
  content::DesktopMediaID media_id =
      GetDesktopStreamsRegistry()->RequestMediaForStreamId(
          request.requested_video_device_id, request.render_process_id,
          request.render_view_id, request.security_origin,
          &original_extension_name);

  // Received invalid device id.
  if (media_id.type == content::DesktopMediaID::TYPE_NONE) {
    callback.Run(devices, content::MEDIA_DEVICE_INVALID_STATE, ui.Pass());
    return;
  }

  bool loopback_audio_supported = false;
#if defined(USE_CRAS) || defined(OS_WIN)
  // Currently loopback audio capture is supported only on Windows and ChromeOS.
  loopback_audio_supported = true;
#endif

  // Audio is only supported for screen capture streams.
  bool capture_audio =
      (media_id.type == content::DesktopMediaID::TYPE_SCREEN &&
       request.audio_type == content::MEDIA_LOOPBACK_AUDIO_CAPTURE &&
       loopback_audio_supported);

  ui = GetDevicesForDesktopCapture(
      devices, media_id, capture_audio, true,
      GetApplicationTitle(web_contents, extension),
      base::UTF8ToUTF16(original_extension_name));

  callback.Run(devices, content::MEDIA_DEVICE_OK, ui.Pass());
}

void MediaCaptureDevicesDispatcher::ProcessScreenCaptureAccessRequest(
    content::WebContents* web_contents,
    const content::MediaStreamRequest& request,
    const content::MediaResponseCallback& callback,
    const extensions::Extension* extension) {
  content::MediaStreamDevices devices;
  scoped_ptr<content::MediaStreamUI> ui;

  DCHECK_EQ(request.video_type, content::MEDIA_DESKTOP_VIDEO_CAPTURE);

  bool loopback_audio_supported = false;
#if defined(USE_CRAS) || defined(OS_WIN)
  // Currently loopback audio capture is supported only on Windows and ChromeOS.
  loopback_audio_supported = true;
#endif

  const bool component_extension =
      extension && extension->location() == extensions::Manifest::COMPONENT;

  const bool screen_capture_enabled =
      CommandLine::ForCurrentProcess()->HasSwitch(
          switches::kEnableUserMediaScreenCapturing) ||
      IsOriginForCasting(request.security_origin) ||
      IsBuiltInExtension(request.security_origin);

  const bool origin_is_secure =
      request.security_origin.SchemeIsSecure() ||
      request.security_origin.SchemeIs(extensions::kExtensionScheme) ||
      CommandLine::ForCurrentProcess()->HasSwitch(
          switches::kAllowHttpScreenCapture);

  // Approve request only when the following conditions are met:
  //  1. Screen capturing is enabled via command line switch or white-listed for
  //     the given origin.
  //  2. Request comes from a page with a secure origin or from an extension.
  if (screen_capture_enabled && origin_is_secure) {
    // Get title of the calling application prior to showing the message box.
    // chrome::ShowMessageBox() starts a nested message loop which may allow
    // |web_contents| to be destroyed on the UI thread before the message box
    // is closed. See http://crbug.com/326690.
    base::string16 application_title =
        GetApplicationTitle(web_contents, extension);
#if !defined(OS_ANDROID)
    gfx::NativeWindow parent_window =
        FindParentWindowForWebContents(web_contents);
#else
    gfx::NativeWindow parent_window = NULL;
#endif
    web_contents = NULL;

    // For component extensions, bypass message box.
    bool user_approved = false;
    if (!component_extension) {
      base::string16 application_name = base::UTF8ToUTF16(
          extension ? extension->name() : request.security_origin.spec());
      base::string16 confirmation_text = l10n_util::GetStringFUTF16(
          request.audio_type == content::MEDIA_NO_SERVICE ?
              IDS_MEDIA_SCREEN_CAPTURE_CONFIRMATION_TEXT :
              IDS_MEDIA_SCREEN_AND_AUDIO_CAPTURE_CONFIRMATION_TEXT,
          application_name);
      chrome::MessageBoxResult result = chrome::ShowMessageBox(
          parent_window,
          l10n_util::GetStringFUTF16(
              IDS_MEDIA_SCREEN_CAPTURE_CONFIRMATION_TITLE, application_name),
          confirmation_text,
          chrome::MESSAGE_BOX_TYPE_QUESTION);
      user_approved = (result == chrome::MESSAGE_BOX_RESULT_YES);
    }

    if (user_approved || component_extension) {
      content::DesktopMediaID screen_id;
#if defined(OS_CHROMEOS)
      screen_id = content::DesktopMediaID::RegisterAuraWindow(
          ash::Shell::GetInstance()->GetPrimaryRootWindow());
#else  // defined(OS_CHROMEOS)
      screen_id =
          content::DesktopMediaID(content::DesktopMediaID::TYPE_SCREEN,
                                  webrtc::kFullDesktopScreenId);
#endif  // !defined(OS_CHROMEOS)

      bool capture_audio =
          (request.audio_type == content::MEDIA_LOOPBACK_AUDIO_CAPTURE &&
           loopback_audio_supported);

      // Unless we're being invoked from a component extension, register to
      // display the notification for stream capture.
      bool display_notification = !component_extension;

      ui = GetDevicesForDesktopCapture(devices, screen_id, capture_audio,
                                       display_notification, application_title,
                                       application_title);
    }
  }

  callback.Run(
    devices,
    devices.empty() ? content::MEDIA_DEVICE_INVALID_STATE :
                      content::MEDIA_DEVICE_OK,
    ui.Pass());
}

void MediaCaptureDevicesDispatcher::ProcessTabCaptureAccessRequest(
    content::WebContents* web_contents,
    const content::MediaStreamRequest& request,
    const content::MediaResponseCallback& callback,
    const extensions::Extension* extension) {
  content::MediaStreamDevices devices;
  scoped_ptr<content::MediaStreamUI> ui;

#if defined(OS_ANDROID)
  // Tab capture is not supported on Android.
  callback.Run(devices, content::MEDIA_DEVICE_TAB_CAPTURE_FAILURE, ui.Pass());
#else  // defined(OS_ANDROID)
  Profile* profile =
      Profile::FromBrowserContext(web_contents->GetBrowserContext());
  extensions::TabCaptureRegistry* tab_capture_registry =
      extensions::TabCaptureRegistry::Get(profile);
  if (!tab_capture_registry) {
    NOTREACHED();
    callback.Run(devices, content::MEDIA_DEVICE_INVALID_STATE, ui.Pass());
    return;
  }
  bool tab_capture_allowed =
      tab_capture_registry->VerifyRequest(request.render_process_id,
                                          request.render_view_id);

  if (request.audio_type == content::MEDIA_TAB_AUDIO_CAPTURE &&
      tab_capture_allowed &&
      extension->permissions_data()->HasAPIPermission(
          extensions::APIPermission::kTabCapture)) {
    devices.push_back(content::MediaStreamDevice(
        content::MEDIA_TAB_AUDIO_CAPTURE, std::string(), std::string()));
  }

  if (request.video_type == content::MEDIA_TAB_VIDEO_CAPTURE &&
      tab_capture_allowed &&
      extension->permissions_data()->HasAPIPermission(
          extensions::APIPermission::kTabCapture)) {
    devices.push_back(content::MediaStreamDevice(
        content::MEDIA_TAB_VIDEO_CAPTURE, std::string(), std::string()));
  }

  if (!devices.empty()) {
    ui = media_stream_capture_indicator_->RegisterMediaStream(
        web_contents, devices);
  }
  callback.Run(
    devices,
    devices.empty() ? content::MEDIA_DEVICE_INVALID_STATE :
                      content::MEDIA_DEVICE_OK,
    ui.Pass());
#endif  // !defined(OS_ANDROID)
}

void MediaCaptureDevicesDispatcher::
    ProcessMediaAccessRequestFromPlatformAppOrExtension(
        content::WebContents* web_contents,
        const content::MediaStreamRequest& request,
        const content::MediaResponseCallback& callback,
        const extensions::Extension* extension) {

  // TODO(vrk): This code is largely duplicated in
  // MediaStreamDevicesController::Accept(). Move this code into a shared method
  // between the two classes.

  bool audio_allowed =
      request.audio_type == content::MEDIA_DEVICE_AUDIO_CAPTURE &&
      extension->permissions_data()->HasAPIPermission(
          extensions::APIPermission::kAudioCapture);
  bool video_allowed =
      request.video_type == content::MEDIA_DEVICE_VIDEO_CAPTURE &&
      extension->permissions_data()->HasAPIPermission(
          extensions::APIPermission::kVideoCapture);

  bool get_default_audio_device = audio_allowed;
  bool get_default_video_device = video_allowed;

  content::MediaStreamDevices devices;

  // Get the exact audio or video device if an id is specified.
  if (audio_allowed && !request.requested_audio_device_id.empty()) {
    const content::MediaStreamDevice* audio_device =
        GetRequestedAudioDevice(request.requested_audio_device_id);
    if (audio_device) {
      devices.push_back(*audio_device);
      get_default_audio_device = false;
    }
  }
  if (video_allowed && !request.requested_video_device_id.empty()) {
    const content::MediaStreamDevice* video_device =
        GetRequestedVideoDevice(request.requested_video_device_id);
    if (video_device) {
      devices.push_back(*video_device);
      get_default_video_device = false;
    }
  }

  // If either or both audio and video devices were requested but not
  // specified by id, get the default devices.
  if (get_default_audio_device || get_default_video_device) {
    Profile* profile =
        Profile::FromBrowserContext(web_contents->GetBrowserContext());
    GetDefaultDevicesForProfile(profile,
                                get_default_audio_device,
                                get_default_video_device,
                                &devices);
  }

  scoped_ptr<content::MediaStreamUI> ui;
  if (!devices.empty()) {
    ui = media_stream_capture_indicator_->RegisterMediaStream(
        web_contents, devices);
  }
  callback.Run(
    devices,
    devices.empty() ? content::MEDIA_DEVICE_INVALID_STATE :
                      content::MEDIA_DEVICE_OK,
    ui.Pass());
}

void MediaCaptureDevicesDispatcher::ProcessRegularMediaAccessRequest(
    content::WebContents* web_contents,
    const content::MediaStreamRequest& request,
    const content::MediaResponseCallback& callback) {
  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));

  RequestsQueue& queue = pending_requests_[web_contents];
  queue.push_back(PendingAccessRequest(request, callback));

  // If this is the only request then show the infobar.
  if (queue.size() == 1)
    ProcessQueuedAccessRequest(web_contents);
}

void MediaCaptureDevicesDispatcher::ProcessQueuedAccessRequest(
    content::WebContents* web_contents) {
  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));

  std::map<content::WebContents*, RequestsQueue>::iterator it =
      pending_requests_.find(web_contents);

  if (it == pending_requests_.end() || it->second.empty()) {
    // Don't do anything if the tab was closed.
    return;
  }

  DCHECK(!it->second.empty());

  if (PermissionBubbleManager::Enabled() ||
      MediaStreamPermissionBubbleExperimentEnabled()) {
    scoped_ptr<MediaStreamDevicesController> controller(
        new MediaStreamDevicesController(web_contents,
            it->second.front().request,
            base::Bind(&MediaCaptureDevicesDispatcher::OnAccessRequestResponse,
                       base::Unretained(this), web_contents)));
    if (controller->DismissInfoBarAndTakeActionOnSettings())
      return;
    PermissionBubbleManager* bubble_manager =
        PermissionBubbleManager::FromWebContents(web_contents);
    if (bubble_manager)
      bubble_manager->AddRequest(controller.release());
    return;
  }

  // TODO(gbillock): delete this block and the MediaStreamInfoBarDelegate
  // when we've transitioned to bubbles. (crbug/337458)
  MediaStreamInfoBarDelegate::Create(
      web_contents, it->second.front().request,
      base::Bind(&MediaCaptureDevicesDispatcher::OnAccessRequestResponse,
                 base::Unretained(this), web_contents));
}

void MediaCaptureDevicesDispatcher::OnAccessRequestResponse(
    content::WebContents* web_contents,
    const content::MediaStreamDevices& devices,
    content::MediaStreamRequestResult result,
    scoped_ptr<content::MediaStreamUI> ui) {
  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));

  std::map<content::WebContents*, RequestsQueue>::iterator it =
      pending_requests_.find(web_contents);
  if (it == pending_requests_.end()) {
    // WebContents has been destroyed. Don't need to do anything.
    return;
  }

  RequestsQueue& queue(it->second);
  if (queue.empty())
    return;

  content::MediaResponseCallback callback = queue.front().callback;
  queue.pop_front();

  if (!queue.empty()) {
    // Post a task to process next queued request. It has to be done
    // asynchronously to make sure that calling infobar is not destroyed until
    // after this function returns.
    BrowserThread::PostTask(
        BrowserThread::UI, FROM_HERE,
        base::Bind(&MediaCaptureDevicesDispatcher::ProcessQueuedAccessRequest,
                   base::Unretained(this), web_contents));
  }

  callback.Run(devices, result, ui.Pass());
}

void MediaCaptureDevicesDispatcher::GetDefaultDevicesForProfile(
    Profile* profile,
    bool audio,
    bool video,
    content::MediaStreamDevices* devices) {
  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
  DCHECK(audio || video);

  PrefService* prefs = profile->GetPrefs();
  std::string default_device;
  if (audio) {
    default_device = prefs->GetString(prefs::kDefaultAudioCaptureDevice);
    const content::MediaStreamDevice* device =
        GetRequestedAudioDevice(default_device);
    if (!device)
      device = GetFirstAvailableAudioDevice();
    if (device)
      devices->push_back(*device);
  }

  if (video) {
    default_device = prefs->GetString(prefs::kDefaultVideoCaptureDevice);
    const content::MediaStreamDevice* device =
        GetRequestedVideoDevice(default_device);
    if (!device)
      device = GetFirstAvailableVideoDevice();
    if (device)
      devices->push_back(*device);
  }
}

const content::MediaStreamDevice*
MediaCaptureDevicesDispatcher::GetRequestedAudioDevice(
    const std::string& requested_audio_device_id) {
  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
  const content::MediaStreamDevices& audio_devices = GetAudioCaptureDevices();
  const content::MediaStreamDevice* const device =
      FindDeviceWithId(audio_devices, requested_audio_device_id);
  return device;
}

const content::MediaStreamDevice*
MediaCaptureDevicesDispatcher::GetFirstAvailableAudioDevice() {
  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
  const content::MediaStreamDevices& audio_devices = GetAudioCaptureDevices();
  if (audio_devices.empty())
    return NULL;
  return &(*audio_devices.begin());
}

const content::MediaStreamDevice*
MediaCaptureDevicesDispatcher::GetRequestedVideoDevice(
    const std::string& requested_video_device_id) {
  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
  const content::MediaStreamDevices& video_devices = GetVideoCaptureDevices();
  const content::MediaStreamDevice* const device =
      FindDeviceWithId(video_devices, requested_video_device_id);
  return device;
}

const content::MediaStreamDevice*
MediaCaptureDevicesDispatcher::GetFirstAvailableVideoDevice() {
  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
  const content::MediaStreamDevices& video_devices = GetVideoCaptureDevices();
  if (video_devices.empty())
    return NULL;
  return &(*video_devices.begin());
}

void MediaCaptureDevicesDispatcher::DisableDeviceEnumerationForTesting() {
  is_device_enumeration_disabled_ = true;
}

scoped_refptr<MediaStreamCaptureIndicator>
MediaCaptureDevicesDispatcher::GetMediaStreamCaptureIndicator() {
  return media_stream_capture_indicator_;
}

DesktopStreamsRegistry*
MediaCaptureDevicesDispatcher::GetDesktopStreamsRegistry() {
  if (!desktop_streams_registry_)
    desktop_streams_registry_.reset(new DesktopStreamsRegistry());
  return desktop_streams_registry_.get();
}

void MediaCaptureDevicesDispatcher::OnAudioCaptureDevicesChanged() {
  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
  BrowserThread::PostTask(
      BrowserThread::UI, FROM_HERE,
      base::Bind(
          &MediaCaptureDevicesDispatcher::NotifyAudioDevicesChangedOnUIThread,
          base::Unretained(this)));
}

void MediaCaptureDevicesDispatcher::OnVideoCaptureDevicesChanged() {
  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
  BrowserThread::PostTask(
      BrowserThread::UI, FROM_HERE,
      base::Bind(
          &MediaCaptureDevicesDispatcher::NotifyVideoDevicesChangedOnUIThread,
          base::Unretained(this)));
}

void MediaCaptureDevicesDispatcher::OnMediaRequestStateChanged(
    int render_process_id,
    int render_view_id,
    int page_request_id,
    const GURL& security_origin,
    const content::MediaStreamDevice& device,
    content::MediaRequestState state) {
  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
  BrowserThread::PostTask(
      BrowserThread::UI, FROM_HERE,
      base::Bind(
          &MediaCaptureDevicesDispatcher::UpdateMediaRequestStateOnUIThread,
          base::Unretained(this), render_process_id, render_view_id,
          page_request_id, security_origin, device, state));
}

void MediaCaptureDevicesDispatcher::OnAudioStreamPlaying(
    int render_process_id,
    int render_frame_id,
    int stream_id,
    const ReadPowerAndClipCallback& read_power_callback) {
  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
#if defined(AUDIO_STREAM_MONITORING)
  BrowserThread::PostTask(
      BrowserThread::UI,
      FROM_HERE,
      base::Bind(&StartAudioStreamMonitoringOnUIThread,
                 render_process_id,
                 render_frame_id,
                 stream_id,
                 read_power_callback));
#endif
}

void MediaCaptureDevicesDispatcher::OnAudioStreamStopped(
    int render_process_id,
    int render_frame_id,
    int stream_id) {
  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
#if defined(AUDIO_STREAM_MONITORING)
  BrowserThread::PostTask(
      BrowserThread::UI,
      FROM_HERE,
      base::Bind(&StopAudioStreamMonitoringOnUIThread,
                 render_process_id,
                 render_frame_id,
                 stream_id));
#endif
}

void MediaCaptureDevicesDispatcher::OnCreatingAudioStream(
    int render_process_id,
    int render_frame_id) {
  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
  BrowserThread::PostTask(
      BrowserThread::UI, FROM_HERE,
      base::Bind(
          &MediaCaptureDevicesDispatcher::OnCreatingAudioStreamOnUIThread,
          base::Unretained(this), render_process_id, render_frame_id));
}

void MediaCaptureDevicesDispatcher::NotifyAudioDevicesChangedOnUIThread() {
  MediaStreamDevices devices = GetAudioCaptureDevices();
  FOR_EACH_OBSERVER(Observer, observers_,
                    OnUpdateAudioDevices(devices));
}

void MediaCaptureDevicesDispatcher::NotifyVideoDevicesChangedOnUIThread() {
  MediaStreamDevices devices = GetVideoCaptureDevices();
  FOR_EACH_OBSERVER(Observer, observers_,
                    OnUpdateVideoDevices(devices));
}

void MediaCaptureDevicesDispatcher::UpdateMediaRequestStateOnUIThread(
    int render_process_id,
    int render_view_id,
    int page_request_id,
    const GURL& security_origin,
    const content::MediaStreamDevice& device,
    content::MediaRequestState state) {
  // Track desktop capture sessions.  Tracking is necessary to avoid unbalanced
  // session counts since not all requests will reach MEDIA_REQUEST_STATE_DONE,
  // but they will all reach MEDIA_REQUEST_STATE_CLOSING.
  if (device.type == content::MEDIA_DESKTOP_VIDEO_CAPTURE) {
    if (state == content::MEDIA_REQUEST_STATE_DONE) {
      DesktopCaptureSession session = { render_process_id, render_view_id,
                                        page_request_id };
      desktop_capture_sessions_.push_back(session);
    } else if (state == content::MEDIA_REQUEST_STATE_CLOSING) {
      for (DesktopCaptureSessions::iterator it =
               desktop_capture_sessions_.begin();
           it != desktop_capture_sessions_.end();
           ++it) {
        if (it->render_process_id == render_process_id &&
            it->render_view_id == render_view_id &&
            it->page_request_id == page_request_id) {
          desktop_capture_sessions_.erase(it);
          break;
        }
      }
    }
  }

  // Cancel the request.
  if (state == content::MEDIA_REQUEST_STATE_CLOSING) {
    bool found = false;
    for (RequestsQueues::iterator rqs_it = pending_requests_.begin();
         rqs_it != pending_requests_.end(); ++rqs_it) {
      RequestsQueue& queue = rqs_it->second;
      for (RequestsQueue::iterator it = queue.begin();
           it != queue.end(); ++it) {
        if (it->request.render_process_id == render_process_id &&
            it->request.render_view_id == render_view_id &&
            it->request.page_request_id == page_request_id) {
          queue.erase(it);
          found = true;
          break;
        }
      }
      if (found)
        break;
    }
  }

#if defined(OS_CHROMEOS)
  if (IsOriginForCasting(security_origin) && IsVideoMediaType(device.type)) {
    // Notify ash that casting state has changed.
    if (state == content::MEDIA_REQUEST_STATE_DONE) {
      ash::Shell::GetInstance()->OnCastingSessionStartedOrStopped(true);
    } else if (state == content::MEDIA_REQUEST_STATE_CLOSING) {
      ash::Shell::GetInstance()->OnCastingSessionStartedOrStopped(false);
    }
  }
#endif

  FOR_EACH_OBSERVER(Observer, observers_,
                    OnRequestUpdate(render_process_id,
                                    render_view_id,
                                    device,
                                    state));
}

void MediaCaptureDevicesDispatcher::OnCreatingAudioStreamOnUIThread(
    int render_process_id,
    int render_frame_id) {
  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
  FOR_EACH_OBSERVER(Observer, observers_,
                    OnCreatingAudioStream(render_process_id, render_frame_id));
#if defined(AUDIO_STREAM_MONITORING)
  content::WebContents* const web_contents =
      content::WebContents::FromRenderFrameHost(
          content::RenderFrameHost::FromID(render_process_id, render_frame_id));
  if (web_contents) {
    // Note: Calling CreateForWebContents() multiple times is valid (see usage
    // info for content::WebContentsUserData).
    AudioStreamMonitor::CreateForWebContents(web_contents);
  }
#endif
}

bool MediaCaptureDevicesDispatcher::IsDesktopCaptureInProgress() {
  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
  return desktop_capture_sessions_.size() > 0;
}


void MediaCaptureDevicesDispatcher::SetTestAudioCaptureDevices(
    const MediaStreamDevices& devices) {
  test_audio_devices_ = devices;
}

void MediaCaptureDevicesDispatcher::SetTestVideoCaptureDevices(
    const MediaStreamDevices& devices) {
  test_video_devices_ = devices;
}