Moving src/webrtc into src/.

In order to eliminate the WebRTC Subtree mirror in Chromium, 
WebRTC is moving the content of the src/webrtc directory up
to the src/ directory.

NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
TBR=tommi@webrtc.org

Bug: chromium:611808
Change-Id: Iac59c5b51b950f174119565bac87955a7994bc38
Reviewed-on: https://webrtc-review.googlesource.com/1560
Commit-Queue: Mirko Bonadei <mbonadei@webrtc.org>
Reviewed-by: Henrik Kjellander <kjellander@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#19845}

rtc_base/thread_checker_impl.h

@@ -0,0 +1,48 @@
+/*
+ *  Copyright (c) 2014 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.
+ */
+
+// Borrowed from Chromium's src/base/threading/thread_checker_impl.h.
+
+#ifndef WEBRTC_RTC_BASE_THREAD_CHECKER_IMPL_H_
+#define WEBRTC_RTC_BASE_THREAD_CHECKER_IMPL_H_
+
+#include "webrtc/rtc_base/criticalsection.h"
+#include "webrtc/rtc_base/platform_thread_types.h"
+
+namespace rtc {
+
+// Real implementation of ThreadChecker, for use in debug mode, or
+// for temporary use in release mode (e.g. to RTC_CHECK on a threading issue
+// seen only in the wild).
+//
+// Note: You should almost always use the ThreadChecker class to get the
+// right version for your build configuration.
+class ThreadCheckerImpl {
+ public:
+  ThreadCheckerImpl();
+  ~ThreadCheckerImpl();
+
+  bool CalledOnValidThread() const;
+
+  // Changes the thread that is checked for in CalledOnValidThread.  This may
+  // be useful when an object may be created on one thread and then used
+  // exclusively on another thread.
+  void DetachFromThread();
+
+ private:
+  CriticalSection lock_;
+  // This is mutable so that CalledOnValidThread can set it.
+  // It's guarded by |lock_|.
+  mutable PlatformThreadRef valid_thread_;
+};
+
+}  // namespace rtc
+
+#endif  // WEBRTC_RTC_BASE_THREAD_CHECKER_IMPL_H_