Mac ÜC: Fix white page hangs

content/browser/gpu/gpu_process_host.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/browser/gpu/gpu_process_host.h"
 
 #include "base/base64.h"
 #include "base/base_switches.h"
 #include "base/basictypes.h"
 #include "base/bind.h"
@@ skipping 885 matching lines @@
     Send(new AcceleratedSurfaceMsg_BufferPresented(params.route_id,
                                                    ack_params));
   }
 
   // Pass the SwapBuffers on to the RenderWidgetHelper to wake up the UI thread
   // if the browser is waiting for a new frame. Otherwise the RenderWidgetHelper
   // will forward to the RenderWidgetHostView via RenderProcessHostImpl and
   // RenderWidgetHostImpl.
   ViewHostMsg_CompositorSurfaceBuffersSwapped_Params view_params;
   view_params.use_native_widget = native_widget;
+  view_params.native_widget_token = native_widget ?
+      RenderWidgetHelper::CreateNativeWidgetSwapToken() : 0;
   view_params.surface_id = params.surface_id;
   view_params.surface_handle = params.surface_handle;
   view_params.route_id = params.route_id;
   view_params.size = params.size;
   view_params.scale_factor = params.scale_factor;
   view_params.gpu_process_host_id = host_id_;
   view_params.latency_info = params.latency_info;
-  if (helper) {
-    helper->DidReceiveBackingStoreMsg(
-        ViewHostMsg_CompositorSurfaceBuffersSwapped(
-            render_widget_id,
-            view_params));
-  } else if (native_widget) {
+  // Always post a task to handle native widget messages, in case the helper
+  // that the message is sent to is destroyed before the message is handled.
+  if (native_widget) {
     BrowserThread::PostTask(
         BrowserThread::UI,
         FROM_HERE,
         base::Bind(&RenderWidgetHelper::OnNativeSurfaceBuffersSwappedOnUIThread,
                        view_params));
   }
+  if (helper) {
+    helper->DidReceiveBackingStoreMsg(
+        ViewHostMsg_CompositorSurfaceBuffersSwapped(
+            render_widget_id,
+            view_params));
+  }
+
 }
 #endif  // OS_MACOSX
 
 void GpuProcessHost::OnProcessLaunched() {
   UMA_HISTOGRAM_TIMES("GPU.GPUProcessLaunchTime",
                       base::TimeTicks::Now() - init_start_time_);
 }
 
 void GpuProcessHost::OnProcessCrashed(int exit_code) {
   SendOutstandingReplies();
@@ skipping 204 matching lines @@
   TRACE_EVENT0("gpu", "GpuProcessHost::OnCacheShader");
   ClientIdToShaderCacheMap::iterator iter =
       client_id_to_shader_cache_.find(client_id);
   // If the cache doesn't exist then this is an off the record profile.
   if (iter == client_id_to_shader_cache_.end())
     return;
   iter->second->Cache(GetShaderPrefixKey() + ":" + key, shader);
 }
 
 }  // namespace content