Inform the WebFrameClient of BeforeUnload/Unload handlers

public/web/WebFrameClient.h

 /*
  * Copyright (C) 2011, 2012 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 593 matching lines @@
     // Fullscreen ----------------------------------------------------------
 
     // Called to enter/exit fullscreen mode. If enterFullScreen returns true,
     // then WebWidget::{will,Did}EnterFullScreen should bound resizing the
     // WebWidget into fullscreen mode. Similarly, when exitFullScreen is
     // called, WebWidget::{will,Did}ExitFullScreen should bound resizing the
     // WebWidget out of fullscreen mode.
     virtual bool enterFullscreen() { return false; }
     virtual bool exitFullscreen() { return false; }
 
+
+    // Sudden termination --------------------------------------------------
+
+    // Called when an element preventing the sudden termination of the frame is
+    // added or removed. |variation| is the number of elements added, removed if
+    // it is negative. |type| is the type of element (BeforeUnload handler,
+    // Unload handler).
+    enum SuddenTerminationDisablerType {
+        BeforeUnloadHandler,
+        UnloadHandler,
+    };
+    virtual void suddenTerminationDisablerChanged(int variation, SuddenTerminationDisablerType) { }
+
 protected:
     virtual ~WebFrameClient() { }
 };
 
 } // namespace blink
 
 #endif