Make OffscreenCanvas animation in sync with its placeholder canvas's parent frame rate

content/renderer/gpu/render_widget_compositor.cc

 // Copyright (c) 2013 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 "content/renderer/gpu/render_widget_compositor.h"
 
 #include <stddef.h>
 
 #include <cmath>
 #include <limits>
@@ skipping 650 matching lines @@
   return layer_tree_host_->ScheduleMicroBenchmark(name, std::move(value),
                                                   callback);
 }
 
 bool RenderWidgetCompositor::SendMessageToMicroBenchmark(
     int id,
     std::unique_ptr<base::Value> value) {
   return layer_tree_host_->SendMessageToMicroBenchmark(id, std::move(value));
 }
 
+cc::FrameSinkId RenderWidgetCompositor::getFrameSinkId() {
+  return frame_sink_id_;
+}
+
 void RenderWidgetCompositor::setRootLayer(const blink::WebLayer& layer) {
   layer_tree_host_->GetLayerTree()->SetRootLayer(
       static_cast<const cc_blink::WebLayerImpl*>(&layer)->layer());
 }
 
 void RenderWidgetCompositor::clearRootLayer() {
   layer_tree_host_->GetLayerTree()->SetRootLayer(scoped_refptr<cc::Layer>());
 }
 
 cc::AnimationHost* RenderWidgetCompositor::compositorAnimationHost() {
@@ skipping 456 matching lines @@
     float device_scale) {
   layer_tree_host_->GetLayerTree()->SetPaintedDeviceScaleFactor(device_scale);
 }
 
 void RenderWidgetCompositor::SetDeviceColorSpace(
     const gfx::ColorSpace& color_space) {
   layer_tree_host_->GetLayerTree()->SetDeviceColorSpace(color_space);
 }
 
 }  // namespace content