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/sequenced_task_checker_impl.cc

@@ -0,0 +1,63 @@
+/*
+ *  Copyright (c) 2016 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/rtc_base/sequenced_task_checker_impl.h"
+
+#if defined(WEBRTC_MAC)
+#include <dispatch/dispatch.h>
+#endif
+
+#include "webrtc/rtc_base/platform_thread.h"
+#include "webrtc/rtc_base/sequenced_task_checker.h"
+#include "webrtc/rtc_base/task_queue.h"
+
+namespace rtc {
+
+SequencedTaskCheckerImpl::SequencedTaskCheckerImpl()
+    : attached_(true), valid_queue_(TaskQueue::Current()) {}
+
+SequencedTaskCheckerImpl::~SequencedTaskCheckerImpl() {}
+
+bool SequencedTaskCheckerImpl::CalledSequentially() const {
+  QueueId current_queue = TaskQueue::Current();
+#if defined(WEBRTC_MAC)
+  // If we're not running on a TaskQueue, use the system dispatch queue
+  // label as an identifier.
+  if (current_queue == nullptr)
+    current_queue = dispatch_queue_get_label(DISPATCH_CURRENT_QUEUE_LABEL);
+#endif
+  CritScope scoped_lock(&lock_);
+  if (!attached_) {  // true if previously detached.
+    valid_queue_ = current_queue;
+    attached_ = true;
+  }
+  if (!valid_queue_)
+    return thread_checker_.CalledOnValidThread();
+  return valid_queue_ == current_queue;
+}
+
+void SequencedTaskCheckerImpl::Detach() {
+  CritScope scoped_lock(&lock_);
+  attached_ = false;
+  valid_queue_ = nullptr;
+  thread_checker_.DetachFromThread();
+}
+
+namespace internal {
+
+SequencedTaskCheckerScope::SequencedTaskCheckerScope(
+    const SequencedTaskChecker* checker) {
+  RTC_DCHECK(checker->CalledSequentially());
+}
+
+SequencedTaskCheckerScope::~SequencedTaskCheckerScope() {}
+
+}  // namespace internal
+}  // namespace rtc