Refactor ImageBuffer to make OffscreenCanvas match HTMLCanvasElement

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

Index: third_party/WebKit/Source/core/html/canvas/CanvasRenderingContextHost.h
diff --git a/third_party/WebKit/Source/core/html/canvas/CanvasRenderingContextHost.h b/third_party/WebKit/Source/core/html/canvas/CanvasRenderingContextHost.h
index f123b733d6e4822df6800a42d4282950e9e0ce1c..8aa50c5575a0538f73b58916ddc4b463f24a45b1 100644
--- a/third_party/WebKit/Source/core/html/canvas/CanvasRenderingContextHost.h
+++ b/third_party/WebKit/Source/core/html/canvas/CanvasRenderingContextHost.h
@@ -13,6 +13,7 @@
 #include "core/events/EventTarget.h"
 #include "platform/geometry/FloatRect.h"
 #include "platform/geometry/IntSize.h"
+#include "platform/graphics/ImageBuffer.h"
 #include "platform/heap/GarbageCollected.h"
 
 namespace blink {
@@ -44,6 +45,10 @@ class CORE_EXPORT CanvasRenderingContextHost : public GarbageCollectedMixin {
                                ScriptState*,
                                ExceptionState&);
 
+  virtual bool HasImageBuffer() const = 0;
+  virtual void DiscardImageBuffer() = 0;
+  virtual ImageBuffer* GetImageBuffer() const = 0;
+
   // TODO(fserb): remove this.
   virtual bool IsOffscreenCanvas() const { return false; }