Refactor ImageBuffer to make OffscreenCanvas match HTMLCanvasElement

third_party/WebKit/Source/core/html/HTMLCanvasElement.h

 /*
  * Copyright (C) 2004, 2006, 2009, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2007 Alp Toker <alp@atoker.com>
  * Copyright (C) 2010 Torch Mobile (Beijing) Co. Ltd. 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.
@@ skipping 129 matching lines @@
 
   void Paint(GraphicsContext&, const LayoutRect&);
 
   PaintCanvas* DrawingCanvas() const;
   void DisableDeferral(DisableDeferralReason) const;
   PaintCanvas* ExistingDrawingCanvas() const;
 
   CanvasRenderingContext* RenderingContext() const { return context_.Get(); }
 
   void EnsureUnacceleratedImageBuffer();
-  ImageBuffer* Buffer() const;
   PassRefPtr<Image> CopiedImage(SourceDrawingBuffer,
                                 AccelerationHint,
                                 SnapshotReason) const;
   void ClearCopiedImage();
 
   bool OriginClean() const;
   void SetOriginTainted() { origin_clean_ = false; }
 
   AffineTransform BaseTransform() const;
 
   bool Is3d() const;
   bool Is2d() const;
   bool IsAnimated2d() const;
 
-  bool HasImageBuffer() const { return image_buffer_.get(); }
-  void DiscardImageBuffer();
+  bool HasImageBuffer() const override { return !!image_buffer_; }
+  void DiscardImageBuffer() override;
+  ImageBuffer* GetImageBuffer() const override;

[Justin Novosad, 2017/05/01 15:18:57]

This should be called GetOrCreateImageBuffer() IMHO, to make it clear that it
may return non-null even when HasImageBuffer() returns false.

[fserb, 2017/05/02 18:49:30]

done

 
   bool ShouldBeDirectComposited() const;
 
   void PrepareSurfaceForPaintingIfNeeded() const;
 
   const AtomicString ImageSourceURL() const override;
 
   InsertionNotificationRequest InsertedInto(ContainerNode*) override;
 
   bool IsDirty() { return !dirty_rect_.IsEmpty(); }
@@ skipping 159 matching lines @@
   std::unique_ptr<CanvasSurfaceLayerBridge> surface_layer_bridge_;
 
   int num_frames_since_last_rendering_mode_switch_;
   bool pending_rendering_mode_switch_;
   bool did_notify_listeners_for_current_frame_ = false;
 };
 
 }  // namespace blink
 
 #endif  // HTMLCanvasElement_h