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

content/browser/web_contents/web_contents_impl.h

Index: content/browser/web_contents/web_contents_impl.h
diff --git a/content/browser/web_contents/web_contents_impl.h b/content/browser/web_contents/web_contents_impl.h
index 8278efbefb179207529d871450e75c25602ab472..58ead584b063fcb18fcfad1e5390cc13acb456b4 100644
--- a/content/browser/web_contents/web_contents_impl.h
+++ b/content/browser/web_contents/web_contents_impl.h
@@ -328,6 +328,7 @@ class CONTENT_EXPORT WebContentsImpl
   virtual void DidStartLoading(RenderFrameHost* render_frame_host,
                                bool to_different_document) OVERRIDE;
   virtual void SwappedOut(RenderFrameHost* render_frame_host) OVERRIDE;
+  virtual void DidDeferAfterResponseStarted() OVERRIDE;
   virtual void WorkerCrashed(RenderFrameHost* render_frame_host) OVERRIDE;
   virtual void ShowContextMenu(RenderFrameHost* render_frame_host,
                                const ContextMenuParams& params) OVERRIDE;
@@ -625,6 +626,14 @@ class CONTENT_EXPORT WebContentsImpl
   // currently focused frame.
   void SelectRange(const gfx::Point& start, const gfx::Point& end);
 
+  // Notifies the TransitionRequestManager that the main frame navigation is
+  // a transition navigation.
+  void SetHasPendingTransitionRequest(bool has_pending_transition);
+
+  // Notifies the main frame that it can continue navigation (if it was deferred
+  // immediately at first response).
+  void ResumeResponseDeferredAtStart();
+
  private:
   friend class TestNavigationObserver;
   friend class WebContentsAddedObserver;