PlzNavigate: properly execute BeforeUnload on renderer initiated navigations

third_party/WebKit/public/web/WebFrame.h

 /*
  * Copyright (C) 2009 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 236 matching lines @@
 
     // Content ------------------------------------------------------------
 
     virtual WebDocument document() const = 0;
 
     virtual WebPerformance performance() const = 0;
 
 
     // Closing -------------------------------------------------------------
 
-    // Runs beforeunload handlers for this frame, returning false if a
-    // handler suppressed unloading.
-    virtual bool dispatchBeforeUnloadEvent() = 0;
-
     // Runs unload handlers for this frame.
     virtual void dispatchUnloadEvent() = 0;
 
 
     // Scripting ----------------------------------------------------------
 
     // Executes script in the context of the current page.
     virtual void executeScript(const WebScriptSource&) = 0;
 
     // Executes JavaScript in a new world associated with the web frame.
@@ skipping 327 matching lines @@
     WebFrame* m_firstChild;
     WebFrame* m_lastChild;
 
     WebFrame* m_opener;
     WebPrivateOwnPtr<OpenedFrameTracker> m_openedFrameTracker;
 };
 
 } // namespace blink
 
 #endif