Ensure media control goes to transparent(hide) after seek by touch

Source/core/html/shadow/MediaControlElements.h

 /*
  * Copyright (C) 2008, 2009, 2010, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 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.
@@ skipping 24 matching lines @@
 namespace blink {
 
 // ----------------------------
 
 class MediaControlPanelElement final : public MediaControlDivElement {
 public:
     static PassRefPtrWillBeRawPtr<MediaControlPanelElement> create(MediaControls&);
 
     void setIsDisplayed(bool);
 
+    bool isOpaque();
     void makeOpaque();
     void makeTransparent();
 
 private:
     explicit MediaControlPanelElement(MediaControls&);
 
     virtual void defaultEventHandler(Event*) override;
 
     void startTimer();
     void stopTimer();
@@ skipping 196 matching lines @@
     virtual RenderObject* createRenderer(RenderStyle*) override;
 
     IntRect m_videoDisplaySize;
     float m_fontSize;
 };
 
 
 } // namespace blink
 
 #endif // MediaControlElements_h