Mac ÜC: Fix white page hangs

content/browser/renderer_host/render_widget_helper.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_HELPER_H_
 #define CONTENT_BROWSER_RENDERER_HOST_RENDER_WIDGET_HELPER_H_
 
 #include <deque>
 #include <map>
 
@@ skipping 171 matching lines @@
 
   // Called on the IO thread to handle the freeing of a transport DIB
   void FreeTransportDIB(TransportDIB::Id dib_id);
 #endif
 
 #if defined(OS_MACOSX)
   // Retrieve the render process and widget that was associated with an NSView.
   static bool GetRenderWidgetIDForWidget(gfx::AcceleratedWidget native_widget,
                                          int* render_process_id,
                                          int* render_widget_id);
+
+  // To ensure that the message does not get dropped on the floor when
+  // the RenderWidgetHelper it is sent to is destroyed, a task is posted to
+  // handle the message. Get a token to identify this  message, to ensure that
+  // it is handled only once,
+  // TODO(ccameron): Make RenderWidgetHelper message handling less hacky.
+  // http://crbug.com/392031
+  static uint64 CreateNativeWidgetSwapToken();
 #endif
 
  private:
   // A class used to proxy a paint message.  PaintMsgProxy objects are created
   // on the IO thread and destroyed on the UI thread.
   class BackingStoreMsgProxy;
   friend class BackingStoreMsgProxy;
   friend class base::RefCountedThreadSafe<RenderWidgetHelper>;
   friend struct BrowserThread::DeleteOnThread<BrowserThread::IO>;
   friend class base::DeleteHelper<RenderWidgetHelper>;
@@ skipping 63 matching lines @@
   base::AtomicSequenceNumber next_routing_id_;
 
   ResourceDispatcherHostImpl* resource_dispatcher_host_;
 
   DISALLOW_COPY_AND_ASSIGN(RenderWidgetHelper);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_RENDERER_HOST_RENDER_WIDGET_HELPER_H_