Stop exposing --disable-gpu-compositing as a Blink RuntimeEnabledFeature

third_party/WebKit/public/platform/Platform.h

 /*
  * 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 536 matching lines @@
 
   // Creates a new fling animation curve instance for device |deviceSource|
   // with |velocity| and already scrolled |cumulativeScroll| pixels.
   virtual WebGestureCurve* createFlingAnimationCurve(
       WebGestureDevice deviceSource,
       const WebFloatPoint& velocity,
       const WebSize& cumulativeScroll) {
     return nullptr;
   }
 
+  // Whether the command line flag: --disable-gpu-compositing or --disable-gpu
+  // exists or not
+  // NOTE: This function should not be called from core/ and modules/, but
+  // called by platform/graphics/ is fine.
+  virtual bool isGPUCompositingEnabled() { return true; }
+
   // WebRTC ----------------------------------------------------------
 
   // Creates a WebRTCPeerConnectionHandler for RTCPeerConnection.
   // May return null if WebRTC functionality is not avaliable or if it's out of
   // resources.
   virtual WebRTCPeerConnectionHandler* createRTCPeerConnectionHandler(
       WebRTCPeerConnectionHandlerClient*) {
     return nullptr;
   }
 
@@ skipping 123 matching lines @@
  protected:
   Platform();
   virtual ~Platform() {}
 
   WebThread* m_mainThread;
 };
 
 }  // namespace blink
 
 #endif