Add UMA to measure potential impact of Fast Tab Close.

content/browser/web_contents/web_contents_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_WEB_CONTENTS_WEB_CONTENTS_IMPL_H_
 #define CONTENT_BROWSER_WEB_CONTENTS_WEB_CONTENTS_IMPL_H_
 
 #include <map>
 #include <string>
 
@@ skipping 408 matching lines @@
       const content::NativeWebKeyboardEvent& event,
       bool* is_keyboard_shortcut) OVERRIDE;
   virtual void HandleKeyboardEvent(
       const content::NativeWebKeyboardEvent& event) OVERRIDE;
 
   // RenderViewHostManager::Delegate -------------------------------------------
 
   virtual bool CreateRenderViewForRenderManager(
       content::RenderViewHost* render_view_host, int opener_route_id) OVERRIDE;
   virtual void BeforeUnloadFiredFromRenderManager(
-      bool proceed,
+      bool proceed, const base::TimeTicks& proceed_time,
       bool* proceed_to_fire_unload) OVERRIDE;
   virtual void RenderViewGoneFromRenderManager(
       content::RenderViewHost* render_view_host) OVERRIDE;
   virtual void UpdateRenderViewSizeForRenderManager() OVERRIDE;
   virtual void NotifySwappedFromRenderManager() OVERRIDE;
   virtual int CreateOpenerRenderViewsForRenderManager(
       content::SiteInstance* instance) OVERRIDE;
   virtual NavigationControllerImpl& GetControllerForRenderManager() OVERRIDE;
   virtual WebUIImpl* CreateWebUIForRenderManager(const GURL& url) OVERRIDE;
   virtual content::NavigationEntry*
@@ skipping 352 matching lines @@
   // If this tab was created from a renderer using window.open, this will be
   // non-NULL and represent the WebUI of the opening renderer.
   content::WebUI::TypeID opener_web_ui_type_;
 
   // The time that we started to create the new tab page.
   base::TimeTicks new_tab_start_time_;
 
   // The time that we started to close this WebContents.
   base::TimeTicks close_start_time_;
 
+  // The time when onbeforeunload ended.
+  base::TimeTicks before_unload_end_time_;
+
   // The time that this tab was last selected.
   base::TimeTicks last_selected_time_;
 
   // See description above setter.
   bool closed_by_user_gesture_;
 
   // Minimum/maximum zoom percent.
   int minimum_zoom_percent_;
   int maximum_zoom_percent_;
   // If true, the default zoom limits have been overriden for this tab, in which
@@ skipping 16 matching lines @@
   content::NotificationRegistrar registrar_;
 
   // Used during IPC message dispatching so that the handlers can get a pointer
   // to the RVH through which the message was received.
   content::RenderViewHost* message_source_;
 
   DISALLOW_COPY_AND_ASSIGN(WebContentsImpl);
 };
 
 #endif  // CONTENT_BROWSER_WEB_CONTENTS_WEB_CONTENTS_IMPL_H_