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

content/browser/renderer_host/render_view_host_impl.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_VIEW_HOST_IMPL_H_
 #define CONTENT_BROWSER_RENDERER_HOST_RENDER_VIEW_HOST_IMPL_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 631 matching lines @@
   // ensures we don't spam the renderer with multiple beforeunload requests.
   // When either this value or is_waiting_for_unload_ack_ is true, the value of
   // unload_ack_is_for_cross_site_transition_ indicates whether this is for a
   // cross-site transition or a tab close attempt.
   bool is_waiting_for_beforeunload_ack_;
 
   // Set to true when there is a pending ViewMsg_Close message.  Also see
   // is_waiting_for_beforeunload_ack_, unload_ack_is_for_cross_site_transition_.
   bool is_waiting_for_unload_ack_;
 
+  // Set to true when waiting for ViewHostMsg_SwapOut_ACK has timed out.
+  bool has_timed_out_on_unload_;
+
   // Valid only when is_waiting_for_beforeunload_ack_ or
   // is_waiting_for_unload_ack_ is true.  This tells us if the unload request
   // is for closing the entire tab ( = false), or only this RenderViewHost in
   // the case of a cross-site transition ( = true).
   bool unload_ack_is_for_cross_site_transition_;
 
   bool are_javascript_messages_suppressed_;
 
   // True if the render view can be shut down suddenly.
   bool sudden_termination_allowed_;
@@ skipping 35 matching lines @@
   DISALLOW_COPY_AND_ASSIGN(RenderViewHostImpl);
 };
 
 #if defined(COMPILER_MSVC)
 #pragma warning(pop)
 #endif
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_RENDERER_HOST_RENDER_VIEW_HOST_IMPL_H_