Do not dispatch messages when there is no output surface client.

content/renderer/gpu/compositor_output_surface.cc

 // 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.
 
 #include "content/renderer/gpu/compositor_output_surface.h"
 
 #include "base/message_loop_proxy.h"
 #include "content/common/view_messages.h"
 #include "content/renderer/render_thread_impl.h"
 #include "ipc/ipc_forwarding_message_filter.h"
@@ skipping 64 matching lines @@
 }
 
 void CompositorOutputSurface::sendFrameToParentCompositor(
     const WebKit::WebCompositorFrame&) {
   DCHECK(CalledOnValidThread());
   NOTREACHED();
 }
 
 void CompositorOutputSurface::OnMessageReceived(const IPC::Message& message) {
   DCHECK(CalledOnValidThread());
+  if (!client_)
+    return;
   IPC_BEGIN_MESSAGE_MAP(CompositorOutputSurface, message)
     IPC_MESSAGE_HANDLER(ViewMsg_UpdateVSyncParameters, OnUpdateVSyncParameters);
   IPC_END_MESSAGE_MAP()
 }
 
 void CompositorOutputSurface::OnUpdateVSyncParameters(
     base::TimeTicks timebase,
     base::TimeDelta interval) {
   DCHECK(CalledOnValidThread());
   DCHECK(client_);
   double monotonicTimebase = timebase.ToInternalValue() /
       static_cast<double>(base::Time::kMicrosecondsPerSecond);
   double intervalInSeconds = interval.ToInternalValue() /
       static_cast<double>(base::Time::kMicrosecondsPerSecond);
   client_->onVSyncParametersChanged(monotonicTimebase, intervalInSeconds);
 }