Remove PageVisibilityObserver contextDestroyed() notifications.

third_party/WebKit/Source/modules/vibration/VibrationController.h

 /*
  *  Copyright (C) 2012 Samsung Electronics
  *
  *  This library is free software; you can redistribute it and/or
  *  modify it under the terms of the GNU Library General Public
  *  License as published by the Free Software Foundation; either
  *  version 2 of the License, or (at your option) any later version.
  *
  *  This library is distributed in the hope that it will be useful,
  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ skipping 50 matching lines @@
 
   // Whether a pattern is being processed. If this is true, the vibration
   // hardware may currently be active, but during a pause it may be inactive.
   bool isRunning() const { return m_isRunning; }
 
   VibrationPattern pattern() const { return m_pattern; }
 
   DECLARE_VIRTUAL_TRACE();
 
  private:
-  // Inherited from ContextLifecycleObserver and PageVisibilityObserver.
+  // Inherited from ContextLifecycleObserver.
   void contextDestroyed(ExecutionContext*) override;
-  void contextDestroyed(Page*) override;
 
   // Inherited from PageVisibilityObserver.
   void pageVisibilityChanged() override;
 
   // The VibrationManager mojo service. This is reset in |contextDestroyed|
   // and must not be called or recreated after it is reset.
   device::blink::VibrationManagerPtr m_service;
 
   // Timer for calling |doVibrate| after a delay. It is safe to call
   // |startOneshot| when the timer is already running: it may affect the time
   // at which it fires, but |doVibrate| will still be called only once.
   Timer<VibrationController> m_timerDoVibrate;
 
   // Whether a pattern is being processed. The vibration hardware may
   // currently be active, or during a pause it may be inactive.
   bool m_isRunning;
 
   // Whether an async mojo call to cancel is pending.
   bool m_isCallingCancel;
 
   // Whether an async mojo call to vibrate is pending.
   bool m_isCallingVibrate;
 
   VibrationPattern m_pattern;
 };
 
 }  // namespace blink
 
 #endif  // VibrationController_h