Add UMA counter for hung renderers on cross-site navigation.

content/browser/renderer_host/render_widget_helper.h

Index: content/browser/renderer_host/render_widget_helper.h
diff --git a/content/browser/renderer_host/render_widget_helper.h b/content/browser/renderer_host/render_widget_helper.h
index 66fb8bfa6f8b3117420f558370896b5db8569381..4e6b3ba728bfc6602b4668a7271877cc6077b29d 100644
--- a/content/browser/renderer_host/render_widget_helper.h
+++ b/content/browser/renderer_host/render_widget_helper.h
@@ -126,7 +126,7 @@ class RenderWidgetHelper
   // corresponding functions in RenderProcessHost. See those declarations
   // for documentation.
   void CancelResourceRequests(int render_widget_id);
-  void CrossSiteSwapOutACK(const ViewMsg_SwapOut_Params& params);
+  void SimulateSwapOutACK(const ViewMsg_SwapOut_Params& params);
   bool WaitForBackingStoreMsg(int render_widget_id,
                               const base::TimeDelta& max_delay,
                               IPC::Message* msg);
@@ -213,8 +213,9 @@ class RenderWidgetHelper
   // Called on the IO thread to cancel resource requests for the render widget.
   void OnCancelResourceRequests(int render_widget_id);
 
-  // Called on the IO thread to resume a cross-site response.
-  void OnCrossSiteSwapOutACK(const ViewMsg_SwapOut_Params& params);
+  // Called on the IO thread to resume a cross-site response, if the ack is
+  // not received as expected.
+  void OnSimulateSwapOutACK(const ViewMsg_SwapOut_Params& params);
 
 #if defined(OS_MACOSX)
   // Called on destruction to release all allocated transport DIBs