Quickly close tabs/window with long-running unload handlers.

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 6524241ba05bfc3a4df3b55a5ed8e389673d0c79..4f9aa416a9137d16cb164f72293ad03f5fbe4f50 100644
--- a/content/browser/web_contents/web_contents_impl.h
+++ b/content/browser/web_contents/web_contents_impl.h
@@ -255,6 +255,7 @@ class CONTENT_EXPORT WebContentsImpl
   virtual base::TimeTicks GetNewTabStartTime() const OVERRIDE;
   virtual void Close() OVERRIDE;
   virtual void OnCloseStarted() OVERRIDE;
+  virtual void OnUnloadDetachedStarted() OVERRIDE;
   virtual bool ShouldAcceptDragAndDrop() const OVERRIDE;
   virtual void SystemDragEnded() OVERRIDE;
   virtual void UserGestureDone() OVERRIDE;
@@ -834,6 +835,9 @@ class CONTENT_EXPORT WebContentsImpl
   // The time when onbeforeunload ended.
   base::TimeTicks before_unload_end_time_;
 
+  // The time when the tab was removed from view during close.
+  base::TimeTicks unload_detached_start_time_;
+
   // The time that this tab was last selected.
   base::TimeTicks last_selected_time_;