Remove unused show/hideTextTrackDisplay()

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 83 matching lines @@
     void hideMediaControlsTimerFired(Timer<MediaControls>*);
     void startHideMediaControlsTimer();
     void stopHideMediaControlsTimer();
     void resetHideMediaControlsTimer();
 
     // Attempts to show the overlay cast button. If it is covered by another
     // element in the page, it will be hidden.
     void tryShowOverlayCastButton();
 
     void createTextTrackDisplay();
-    void showTextTrackDisplay();
-    void hideTextTrackDisplay();
 
     // Node
     virtual bool isMediaControls() const override { return true; }
     virtual bool willRespondToMouseMoveEvents() override { return true; }
     virtual void defaultEventHandler(Event*) override;
     bool containsRelatedTarget(Event*);
 
     RawPtrWillBeMember<HTMLMediaElement> m_mediaElement;
 
     // Container for the media control elements.
@@ skipping 21 matching lines @@
     unsigned m_hideTimerBehaviorFlags;
     bool m_isMouseOverControls : 1;
     bool m_isPausedForScrubbing : 1;
 };
 
 DEFINE_ELEMENT_TYPE_CASTS(MediaControls, isMediaControls());
 
 }
 
 #endif