Add platform_thread source files and move types from thread_checker_impl to there.

BUG=
R=henrika@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/52529004

Cr-Commit-Position: refs/heads/master@{#9201}
diff --git a/webrtc/base/BUILD.gn b/webrtc/base/BUILD.gn
index a9868e9..8680257 100644
--- a/webrtc/base/BUILD.gn
+++ b/webrtc/base/BUILD.gn
@@ -129,6 +129,8 @@
     "md5digest.h",
     "platform_file.cc",
     "platform_file.h",
+    "platform_thread.cc",
+    "platform_thread.h",
     "safe_conversions.h",
     "safe_conversions_impl.h",
     "stringencode.cc",
diff --git a/webrtc/base/base.gyp b/webrtc/base/base.gyp
index 377b41c..6e197a5 100644
--- a/webrtc/base/base.gyp
+++ b/webrtc/base/base.gyp
@@ -57,6 +57,8 @@
         'md5digest.h',
         'platform_file.cc',
         'platform_file.h',
+        'platform_thread.cc',
+        'platform_thread.h',
         'safe_conversions.h',
         'safe_conversions_impl.h',
         'stringencode.cc',
diff --git a/webrtc/base/platform_thread.cc b/webrtc/base/platform_thread.cc
new file mode 100644
index 0000000..d043c11
--- /dev/null
+++ b/webrtc/base/platform_thread.cc
@@ -0,0 +1,57 @@
+/*
+ *  Copyright (c) 2015 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#include "webrtc/base/platform_thread.h"
+
+#include "webrtc/base/checks.h"
+
+#if defined(WEBRTC_LINUX)
+#include <sys/syscall.h>
+#endif
+
+namespace rtc {
+
+PlatformThreadId CurrentThreadId() {
+  PlatformThreadId ret;
+#if defined(WEBRTC_WIN)
+  ret = GetCurrentThreadId();
+#elif defined(WEBRTC_POSIX)
+#if defined(WEBRTC_MAC) || defined(WEBRTC_IOS)
+  ret = pthread_mach_thread_np(pthread_self());
+#elif defined(WEBRTC_LINUX)
+  ret =  syscall(__NR_gettid);
+#elif defined(WEBRTC_ANDROID)
+  ret = gettid();
+#else
+  // Default implementation for nacl and solaris.
+  ret = reinterpret_cast<pid_t>(pthread_self());
+#endif
+#endif  // defined(WEBRTC_POSIX)
+  DCHECK(ret);
+  return ret;
+}
+
+PlatformThreadRef CurrentThreadRef() {
+#if defined(WEBRTC_WIN)
+  return GetCurrentThreadId();
+#elif defined(WEBRTC_POSIX)
+  return pthread_self();
+#endif
+}
+
+bool IsThreadRefEqual(const PlatformThreadRef& a, const PlatformThreadRef& b) {
+#if defined(WEBRTC_WIN)
+  return a == b;
+#elif defined(WEBRTC_POSIX)
+  return pthread_equal(a, b);
+#endif
+}
+
+}  // namespace rtc
diff --git a/webrtc/base/platform_thread.h b/webrtc/base/platform_thread.h
new file mode 100644
index 0000000..9629066
--- /dev/null
+++ b/webrtc/base/platform_thread.h
@@ -0,0 +1,40 @@
+/*
+ *  Copyright (c) 2015 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#ifndef WEBRTC_BASE_PLATFORM_THREAD_H_
+#define WEBRTC_BASE_PLATFORM_THREAD_H_
+
+#if defined(WEBRTC_WIN)
+#include <winsock2.h>
+#include <windows.h>
+#elif defined(WEBRTC_POSIX)
+#include <pthread.h>
+#include <unistd.h>
+#endif
+
+namespace rtc {
+
+#if defined(WEBRTC_WIN)
+typedef DWORD PlatformThreadId;
+typedef DWORD PlatformThreadRef;
+#elif defined(WEBRTC_POSIX)
+typedef pid_t PlatformThreadId;
+typedef pthread_t PlatformThreadRef;
+#endif
+
+PlatformThreadId CurrentThreadId();
+PlatformThreadRef CurrentThreadRef();
+
+// Compares two thread identifiers for equality.
+bool IsThreadRefEqual(const PlatformThreadRef& a, const PlatformThreadRef& b);
+
+}  // namespace rtc
+
+#endif  // WEBRTC_BASE_PLATFORM_THREAD_H_
diff --git a/webrtc/base/thread_checker_impl.cc b/webrtc/base/thread_checker_impl.cc
index 5d59c99..ea88308 100644
--- a/webrtc/base/thread_checker_impl.cc
+++ b/webrtc/base/thread_checker_impl.cc
@@ -12,50 +12,8 @@
 
 #include "webrtc/base/thread_checker_impl.h"
 
-#include "webrtc/base/checks.h"
-
-#if defined(WEBRTC_LINUX)
-#include <sys/syscall.h>
-#endif
-
 namespace rtc {
 
-PlatformThreadId CurrentThreadId() {
-  PlatformThreadId ret;
-#if defined(WEBRTC_WIN)
-  ret = GetCurrentThreadId();
-#elif defined(WEBRTC_POSIX)
-#if defined(WEBRTC_MAC) || defined(WEBRTC_IOS)
-  ret = pthread_mach_thread_np(pthread_self());
-#elif defined(WEBRTC_LINUX)
-  ret =  syscall(__NR_gettid);
-#elif defined(WEBRTC_ANDROID)
-  ret = gettid();
-#else
-  // Default implementation for nacl and solaris.
-  ret = reinterpret_cast<pid_t>(pthread_self());
-#endif
-#endif  // defined(WEBRTC_POSIX)
-  DCHECK(ret);
-  return ret;
-}
-
-PlatformThreadRef CurrentThreadRef() {
-#if defined(WEBRTC_WIN)
-  return GetCurrentThreadId();
-#elif defined(WEBRTC_POSIX)
-  return pthread_self();
-#endif
-}
-
-bool IsThreadRefEqual(const PlatformThreadRef& a, const PlatformThreadRef& b) {
-#if defined(WEBRTC_WIN)
-  return a == b;
-#elif defined(WEBRTC_POSIX)
-  return pthread_equal(a, b);
-#endif
-}
-
 ThreadCheckerImpl::ThreadCheckerImpl() : valid_thread_(CurrentThreadRef()) {
 }
 
diff --git a/webrtc/base/thread_checker_impl.h b/webrtc/base/thread_checker_impl.h
index 5ad15bb..835c53e 100644
--- a/webrtc/base/thread_checker_impl.h
+++ b/webrtc/base/thread_checker_impl.h
@@ -13,31 +13,11 @@
 #ifndef WEBRTC_BASE_THREAD_CHECKER_IMPL_H_
 #define WEBRTC_BASE_THREAD_CHECKER_IMPL_H_
 
-#if defined(WEBRTC_POSIX)
-#include <pthread.h>
-#include <unistd.h>
-#endif
-
 #include "webrtc/base/criticalsection.h"
+#include "webrtc/base/platform_thread.h"
 
 namespace rtc {
 
-// Used for identifying the current thread. Always an integer value.
-#if defined(WEBRTC_WIN)
-typedef DWORD PlatformThreadId;
-typedef DWORD PlatformThreadRef;
-#elif defined(WEBRTC_POSIX)
-typedef pid_t PlatformThreadId;
-typedef pthread_t PlatformThreadRef;
-#endif
-
-// TODO(tommi): This+PlatformThreadId belongs in a common thread related header.
-PlatformThreadId CurrentThreadId();
-PlatformThreadRef CurrentThreadRef();
-
-// Compares two thread identifiers for equality.
-bool IsThreadRefEqual(const PlatformThreadRef& a, const PlatformThreadRef& b);
-
 // Real implementation of ThreadChecker, for use in debug mode, or
 // for temporary use in release mode (e.g. to CHECK on a threading issue
 // seen only in the wild).