Remove USE(GSTREAMER) and USE(WEBAUDIO_GSTREAMER) guards.

Source/core/platform/graphics/MediaPlayerPrivate.h

 /*
  * Copyright (C) 2009, 2010, 2011, 2012, 2013 Apple 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
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 156 matching lines @@
 #endif
 
     virtual bool requiresTextTrackRepresentation() const { return false; }
     virtual void setTextTrackRepresentation(TextTrackRepresentation*) { }
 
 #if USE(PLATFORM_TEXT_TRACK_MENU)
     virtual bool implementsTextTrackControls() const { return false; }
     virtual PassRefPtr<PlatformTextTrackMenuInterface> textTrackMenu() { return 0; }
 #endif
 
-#if USE(GSTREAMER)
-    virtual void simulateAudioInterruption() { }
-#endif
 };
 
 }
 
 #endif
 #endif