Refactor ImageBuffer to make OffscreenCanvas match HTMLCanvasElement

third_party/WebKit/Source/modules/offscreencanvas2d/OffscreenCanvasRenderingContext2D.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 OffscreenCanvasRenderingContext2D_h
 #define OffscreenCanvasRenderingContext2D_h
 
 #include "core/html/canvas/CanvasContextCreationAttributes.h"
 #include "core/html/canvas/CanvasRenderingContext.h"
 #include "core/html/canvas/CanvasRenderingContextFactory.h"
@@ skipping 41 matching lines @@
   void SetOffscreenCanvasGetContextResult(OffscreenRenderingContext&) final;
   void SetIsHidden(bool) final { NOTREACHED(); }
   void Stop() final { NOTREACHED(); }
   void SetCanvasGetContextResult(RenderingContext&) final {}
   void clearRect(double x, double y, double width, double height) override {
     BaseRenderingContext2D::clearRect(x, y, width, height);
   }
   PassRefPtr<Image> GetImage(AccelerationHint, SnapshotReason) const final;
   ImageData* ToImageData(SnapshotReason) override;
   void Reset() override;
+  void RestoreCanvasMatrixClipStack(PaintCanvas* c) const override {
+    RestoreMatrixClipStack(c);
+  }
 
   // BaseRenderingContext2D implementation
   bool OriginClean() const final;
   void SetOriginTainted() final;
   bool WouldTaintOrigin(CanvasImageSource*, ExecutionContext*) final;
 
   int Width() const final;
   int Height() const final;
 
   bool HasImageBuffer() const final;
@@ skipping 28 matching lines @@
       ScriptState*,
       OffscreenCanvas*,
       const CanvasContextCreationAttributes& attrs);
   DECLARE_VIRTUAL_TRACE();
 
   virtual void NeedsFinalizeFrame() {
     CanvasRenderingContext::NeedsFinalizeFrame();
   }
 
  private:
-  bool needs_matrix_clip_restore_ = false;
-  std::unique_ptr<ImageBuffer> image_buffer_;
-
   bool IsPaintable() const final;
 
   RefPtr<StaticBitmapImage> TransferToStaticBitmapImage();
 
   CanvasColorSpace ColorSpace() const override;
   String ColorSpaceAsString() const override;
   CanvasPixelFormat PixelFormat() const override;
 };
 
 // TODO(fserb): remove this.
 DEFINE_TYPE_CASTS(OffscreenCanvasRenderingContext2D,
                   CanvasRenderingContext,
                   context,
                   context->Is2d() && context->host(),
                   context.Is2d() && context.host());
 
 }  // namespace blink
 
 #endif  // OffscreenCanvasRenderingContext2D_h