Navigation transitions: Block first response until after transitions have run.

content/browser/renderer_host/render_message_filter.h

Index: content/browser/renderer_host/render_message_filter.h
diff --git a/content/browser/renderer_host/render_message_filter.h b/content/browser/renderer_host/render_message_filter.h
index e1f90a8a86560ed2b94f0ac1566b7e6ee5cffea5..6cf4d458faad076cabd3539d9bc9d835312eebff 100644
--- a/content/browser/renderer_host/render_message_filter.h
+++ b/content/browser/renderer_host/render_message_filter.h
@@ -280,6 +280,8 @@ class RenderMessageFilter : public BrowserMessageFilter {
                                  IPC::Message* reply);
   void GpuMemoryBufferAllocated(IPC::Message* reply,
                                 const gfx::GpuMemoryBufferHandle& handle);
+  void OnSetHasPendingTransitionRequest(int render_frame_id,
+                                        bool is_transition);
 
   // Cached resource request dispatcher host and plugin service, guaranteed to
   // be non-null if Init succeeds. We do not own the objects, they are managed