Add UMA to measure potential impact of Fast Tab Close.

content/browser/web_contents/render_view_host_manager.cc

 // 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.
 
 #include "content/browser/web_contents/render_view_host_manager.h"
 
 #include <utility>
 
 #include "base/command_line.h"
 #include "base/logging.h"
@@ skipping 316 matching lines @@
         }
       }
     } else {
       // Current page says to cancel.
       CancelPending();
       cross_navigation_pending_ = false;
     }
   } else {
     // Non-cross site transition means closing the entire tab.
     bool proceed_to_fire_unload;
-    delegate_->BeforeUnloadFiredFromRenderManager(proceed,
+    delegate_->BeforeUnloadFiredFromRenderManager(proceed, proceed_time,
                                                   &proceed_to_fire_unload);
 
     if (proceed_to_fire_unload) {
       // This is not a cross-site navigation, the tab is being closed.
       render_view_host_->ClosePage();
     }
   }
 }
 
 void RenderViewHostManager::OnCrossSiteResponse(int new_render_process_host_id,
@@ skipping 616 matching lines @@
 }
 
 RenderViewHostImpl* RenderViewHostManager::GetSwappedOutRenderViewHost(
     SiteInstance* instance) {
   RenderViewHostMap::iterator iter = swapped_out_hosts_.find(instance->GetId());
   if (iter != swapped_out_hosts_.end())
     return iter->second;
 
   return NULL;
 }