Remove MediaControls::showVolumeSlider()

Source/core/html/shadow/MediaControls.h

 /*
  * Copyright (C) 2011, 2012 Apple Inc. All rights reserved.
  * 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:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 42 matching lines @@
 
     void show();
     void hide();
 
     void bufferingProgressed();
     virtual void playbackStarted();
     void playbackProgressed();
     virtual void playbackStopped();
 
     void updateCurrentTimeDisplay();
-    void showVolumeSlider();
 
     void changedMute();
     void changedVolume();
 
     void changedClosedCaptionsVisibility();
     void refreshClosedCaptionsButtonVisibility();
     void closedCaptionTracksChanged();
 
     void enteredFullscreen();
     void exitedFullscreen();
@@ skipping 52 matching lines @@
     Timer<MediaControls> m_hideFullscreenControlsTimer;
     bool m_isFullscreen;
     bool m_isMouseOverControls;
 };
 
 DEFINE_NODE_TYPE_CASTS(MediaControls, isMediaControls());
 
 }
 
 #endif