Add an heuristic for promoting canvases to GPU acceleration

third_party/WebKit/Source/modules/canvas2d/BaseRenderingContext2D.h

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef BaseRenderingContext2D_h
 #define BaseRenderingContext2D_h
 
 #include "bindings/modules/v8/CSSImageValueOrHTMLImageElementOrHTMLVideoElementOrHTMLCanvasElementOrImageBitmapOrOffscreenCanvas.h"
 #include "bindings/modules/v8/StringOrCanvasGradientOrCanvasPattern.h"
 #include "core/html/ImageData.h"
@@ skipping 224 matching lines @@
   virtual void snapshotStateForFilter() = 0;
 
   virtual void validateStateStack() const = 0;
 
   virtual bool hasAlpha() const = 0;
 
   virtual bool isContextLost() const = 0;
 
   virtual ColorBehavior drawImageColorBehavior() const = 0;
 
+  virtual void willDrawImage(CanvasImageSource*) const {}
+
   void restoreMatrixClipStack(SkCanvas*) const;
 
   DECLARE_VIRTUAL_TRACE();
 
   enum DrawCallType {
     StrokePath = 0,
     FillPath,
     DrawVectorImage,
     DrawBitmapImage,
     FillText,
@@ skipping 214 matching lines @@
   foregroundPaint.setBlendMode(SkBlendMode::kSrcOver);
   c->setMatrix(ctm);
   drawFunc(c, &foregroundPaint);
   c->restore();
   c->setMatrix(ctm);
 }
 
 }  // namespace blink
 
 #endif  // BaseRenderingContext2D_h