Don't use a sleep in the browser's main thread to throttle swapbuffers.

content/browser/renderer_host/render_widget_host_impl.h

 // 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.
 
 #ifndef CONTENT_BROWSER_RENDERER_HOST_RENDER_WIDGET_HOST_IMPL_H_
 #define CONTENT_BROWSER_RENDERER_HOST_RENDER_WIDGET_HOST_IMPL_H_
 
 #include <deque>
 #include <list>
 #include <map>
@@ skipping 419 matching lines @@
   // Called by the view in response to OnSwapCompositorFrame.
   static void SendSwapCompositorFrameAck(
       int32 route_id, int renderer_host_id, const cc::CompositorFrameAck& ack);
 
   // Called by the view in response to AcceleratedSurfaceBuffersSwapped for
   // platforms that support deferred GPU process descheduling. This does
   // nothing if the compositor thread is enabled.
   // TODO(jbates) Once the compositor thread is always on, this can be removed.
   void AcknowledgeSwapBuffersToRenderer();
 
+  bool is_threaded_compositing_enabled() const {
+    return is_threaded_compositing_enabled_;
+  }
+
 #if defined(USE_AURA)
   // Called by the view when the parent changes. If a parent isn't available,
   // NULL is used.
   void ParentChanged(gfx::NativeViewId new_parent);
 #endif
 
   // Signals that the compositing surface was updated, e.g. after a lost context
   // event.
   void CompositingSurfaceUpdated();
 
@@ skipping 480 matching lines @@
   int64 last_input_number_;
 
   BrowserRenderingStats rendering_stats_;
 
   DISALLOW_COPY_AND_ASSIGN(RenderWidgetHostImpl);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_RENDERER_HOST_RENDER_WIDGET_HOST_IMPL_H_