Adds BeginFrameControl via DevTools.

ui/compositor/compositor.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 "ui/compositor/compositor.h"
 
 #include <stddef.h>
 
 #include <algorithm>
 #include <deque>
@@ skipping 356 matching lines @@
   context_factory_->SetAuthoritativeVSyncInterval(this, interval);
   vsync_manager_->SetAuthoritativeVSyncInterval(interval);
 }
 
 void Compositor::SetDisplayVSyncParameters(base::TimeTicks timebase,
                                            base::TimeDelta interval) {
   context_factory_->SetDisplayVSyncParameters(this, timebase, interval);
   vsync_manager_->UpdateVSyncParameters(timebase, interval);
 }
 
+void Compositor::SwapBeginFrameSource(
+    std::unique_ptr<cc::BeginFrameSource>* begin_frame_source) {
+  context_factory_->SwapBeginFrameSource(this, begin_frame_source);
+}
+
 void Compositor::SetAcceleratedWidget(gfx::AcceleratedWidget widget) {
   // This function should only get called once.
   DCHECK(!widget_valid_);
   widget_ = widget;
   widget_valid_ = true;
   if (compositor_frame_sink_requested_)
     context_factory_->CreateCompositorFrameSink(weak_ptr_factory_.GetWeakPtr());
 }
 
 gfx::AcceleratedWidget Compositor::ReleaseAcceleratedWidget() {
@@ skipping 139 matching lines @@
   for (auto& observer : observer_list_)
     observer.OnCompositingLockStateChanged(this);
 }
 
 void Compositor::CancelCompositorLock() {
   if (compositor_lock_)
     compositor_lock_->CancelLock();
 }
 
 }  // namespace ui