Make disable vsync run the renderer independently

cc/test/fake_external_begin_frame_source.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 "cc/test/fake_external_begin_frame_source.h"
 
 #include "base/location.h"
 #include "base/single_thread_task_runner.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "base/time/time.h"
@@ skipping 40 matching lines @@
   DCHECK(obs);
   DCHECK(observers_.find(obs) != observers_.end());
 
   observers_.erase(obs);
   if (observers_.empty())
     begin_frame_task_.Cancel();
   if (client_)
     client_->OnRemoveObserver(obs);
 }
 
+bool FakeExternalBeginFrameSource::IsThrottled() const {
+  return true;
+}
+
 void FakeExternalBeginFrameSource::TestOnBeginFrame(
     const BeginFrameArgs& args) {
   DCHECK(CalledOnValidThread());
   std::set<BeginFrameObserver*> observers(observers_);
   for (auto* obs : observers)
     obs->OnBeginFrame(args);
   if (tick_automatically_)
     PostTestOnBeginFrame();
 }
 
 void FakeExternalBeginFrameSource::PostTestOnBeginFrame() {
   begin_frame_task_.Reset(
       base::Bind(&FakeExternalBeginFrameSource::TestOnBeginFrame,
                  weak_ptr_factory_.GetWeakPtr()));
   base::ThreadTaskRunnerHandle::Get()->PostDelayedTask(
       FROM_HERE,
       base::Bind(begin_frame_task_.callback(),
                  CreateBeginFrameArgsForTesting(BEGINFRAME_FROM_HERE)),
       base::TimeDelta::FromMilliseconds(milliseconds_per_frame_));
 }
 
 }  // namespace cc