Removing canvas rendering mode switching feature

third_party/WebKit/Source/core/html/canvas/CanvasRenderingContext.h

 /*
  * Copyright (C) 2009 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 144 matching lines @@
   virtual unsigned HitRegionsCount() const { return 0; }
   virtual void setFont(const String&) {}
   virtual void StyleDidChange(const ComputedStyle* old_style,
                               const ComputedStyle& new_style) {}
   virtual HitTestCanvasResult* GetControlAndIdIfHitRegionExists(
       const LayoutPoint& location) {
     NOTREACHED();
     return HitTestCanvasResult::Create(String(), nullptr);
   }
   virtual String GetIdFromControl(const Element* element) { return String(); }
-  virtual bool IsAccelerationOptimalForCanvasContent() const { return true; }
   virtual void ResetUsageTracking(){};
 
   // WebGL-specific interface
   virtual bool Is3d() const { return false; }
   virtual void SetFilterQuality(SkFilterQuality) { NOTREACHED(); }
   virtual void Reshape(int width, int height) { NOTREACHED(); }
   virtual void MarkLayerComposited() { NOTREACHED(); }
   virtual ImageData* PaintRenderingResultsToImageData(SourceDrawingBuffer) {
     NOTREACHED();
     return nullptr;
@@ skipping 31 matching lines @@
   HashSet<String> clean_urls_;
   HashSet<String> dirty_urls_;
   CanvasColorParams color_params_;
   CanvasContextCreationAttributes creation_attributes_;
   bool finalize_frame_scheduled_ = false;
 };
 
 }  // namespace blink
 
 #endif