cc: Only call didCompleteSwapBuffers() when in threaded mode.

cc/delegating_renderer.cc

 // Copyright 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 "cc/delegating_renderer.h"
 
 #include <set>
 #include <string>
 #include <vector>
 
@@ skipping 159 matching lines @@
 }
 
 void DelegatingRenderer::getFramebufferPixels(void *pixels,
                                               const gfx::Rect& rect) {
   NOTIMPLEMENTED();
 }
 
 void DelegatingRenderer::receiveCompositorFrameAck(
     const CompositorFrameAck& ack) {
   resource_provider_->receiveFromParent(ack.resources);
-  m_client->onSwapBuffersComplete();
+  if (m_client->hasImplThread())
+    m_client->onSwapBuffersComplete();
 }
 
 
 bool DelegatingRenderer::isContextLost() {
   WebGraphicsContext3D* context3d = resource_provider_->graphicsContext3D();
   if (!context3d)
     return false;
   return context3d->getGraphicsResetStatusARB() != GL_NO_ERROR;
 }
 
 void DelegatingRenderer::setVisible(bool visible) {
   visible_ = visible;
 }
 
 void DelegatingRenderer::onContextLost() {
   m_client->didLoseOutputSurface();
 }
 
 }  // namespace cc