[cc]: Add a BeginMainFrameNotExpectedSoon signal and route it to the RendererScheduler.

content/renderer/scheduler/null_renderer_scheduler.cc

 // Copyright 2014 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/scheduler/null_renderer_scheduler.h"
 
 #include "base/bind.h"
 #include "base/message_loop/message_loop_proxy.h"
 
 namespace content {
@@ skipping 50 matching lines @@
 }
 
 scoped_refptr<SingleThreadIdleTaskRunner>
 NullRendererScheduler::IdleTaskRunner() {
   return idle_task_runner_;
 }
 
 void NullRendererScheduler::WillBeginFrame(const cc::BeginFrameArgs& args) {
 }
 
+void NullRendererScheduler::BeginFrameNotExpectedSoon() {
+}
+
 void NullRendererScheduler::DidCommitFrameToCompositor() {
 }
 
 void NullRendererScheduler::DidReceiveInputEventOnCompositorThread(
     const blink::WebInputEvent& web_input_event) {
 }
 
 void NullRendererScheduler::DidAnimateForInputOnCompositorThread() {
 }
 
 bool NullRendererScheduler::IsHighPriorityWorkAnticipated() {
   return false;
 }
 
 bool NullRendererScheduler::ShouldYieldForHighPriorityWork() {
   return false;
 }
 
 void NullRendererScheduler::Shutdown() {
 }
 
 }  // namespace content