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

content/public/browser/web_contents.h

Index: content/public/browser/web_contents.h
diff --git a/content/public/browser/web_contents.h b/content/public/browser/web_contents.h
index 78a498552de5e9cebdc9a0e9d46c0e19d49d9f0e..246877352fe3ffee9488f830a2186f083c1ed660 100644
--- a/content/public/browser/web_contents.h
+++ b/content/public/browser/web_contents.h
@@ -310,6 +310,18 @@ class WebContents : public PageNavigator,
   // times, subsequent calls are ignored.
   virtual void OnCloseStarted() = 0;
 
+  // Notification that tab closing was cancelled. This can happen when a user
+  // cancels a window close via another tab's beforeunload dialog.
+  virtual void OnCloseCanceled() = 0;
+
+  // Set the time during close when unload is started. Normally, this is set
+  // after the beforeunload dialog. However, for a window close, it is set
+  // after all the beforeunload dialogs have finished.
+  virtual void OnUnloadStarted() = 0;
+
+  // Set the time during close when the tab is no longer visible.
+  virtual void OnUnloadDetachedStarted() = 0;
+
   // Returns true if underlying WebContentsView should accept drag-n-drop.
   virtual bool ShouldAcceptDragAndDrop() const = 0;