Make OffscreenCanvas an EventTarget

third_party/WebKit/Source/modules/webgl/WebGLRenderingContextBase.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 573 matching lines @@
 
   PassRefPtr<Image> getImage(AccelerationHint, SnapshotReason) const override;
   ImageData* toImageData(SnapshotReason) const override;
   void setFilterQuality(SkFilterQuality) override;
   bool isWebGL2OrHigher() { return version() >= 2; }
 
   void getHTMLOrOffscreenCanvas(HTMLCanvasElementOrOffscreenCanvas&) const;
 
   void commit(ScriptState*, ExceptionState&);
 
+  ExecutionContext* getExecutionContext() final {
+    return m_executionContext.get();
+  }
+
  protected:
   friend class EXTDisjointTimerQuery;
   friend class EXTDisjointTimerQueryWebGL2;
   friend class WebGLDrawBuffers;
   friend class WebGLFramebuffer;
   friend class WebGLObject;
   friend class WebGLContextObject;
   friend class OESVertexArrayObject;
   friend class WebGLDebugShaders;
   friend class WebGLCompressedTextureASTC;
@@ skipping 11 matching lines @@
   // To allow V8WebGL[2]RenderingContext to call visitChildDOMWrappers.
   friend class V8WebGLRenderingContext;
 
   WebGLRenderingContextBase(HTMLCanvasElement*,
                             std::unique_ptr<WebGraphicsContext3DProvider>,
                             const CanvasContextCreationAttributes&,
                             unsigned);
   WebGLRenderingContextBase(OffscreenCanvas*,
                             std::unique_ptr<WebGraphicsContext3DProvider>,
                             const CanvasContextCreationAttributes&,
+                            ExecutionContext*,
                             unsigned);
   PassRefPtr<DrawingBuffer> createDrawingBuffer(
       std::unique_ptr<WebGraphicsContext3DProvider>,
       DrawingBuffer::ChromiumImageUsage);
   void setupFlags();
 
   // CanvasRenderingContext implementation.
   bool is3d() const override { return true; }
   bool isAccelerated() const override { return true; }
   void setIsHidden(bool) override;
@@ skipping 937 matching lines @@
                         GLenum format,
                         GLenum type,
                         DOMArrayBufferView* pixels,
                         GLuint offset);
 
  private:
   WebGLRenderingContextBase(HTMLCanvasElement*,
                             OffscreenCanvas*,
                             std::unique_ptr<WebGraphicsContext3DProvider>,
                             const CanvasContextCreationAttributes&,
+                            ExecutionContext*,
                             unsigned);
   static std::unique_ptr<WebGraphicsContext3DProvider>
   createContextProviderInternal(HTMLCanvasElement*,
                                 ScriptState*,
                                 const CanvasContextCreationAttributes&,
                                 unsigned);
   void texImageCanvasByGPU(HTMLCanvasElement*, GLuint, GLenum, GLenum, GLint);
   void texImageBitmapByGPU(ImageBitmap*, GLuint, GLenum, GLenum, GLint, bool);
 
   const unsigned m_version;
 
+  Member<ExecutionContext> m_executionContext;

[Justin Novosad, 2016/11/14 16:41:00]

Storing this in the rendering context is unnecessary complexity IMHO. You should
just store is in OffscreenCanvas.

[xidachen, 2016/11/14 18:48:12]

Done. It does make things much simpler.

+
   bool isPaintable() const final { return drawingBuffer(); }
 };
 
 DEFINE_TYPE_CASTS(WebGLRenderingContextBase,
                   CanvasRenderingContext,
                   context,
                   context->is3d(),
                   context.is3d());
 
 }  // namespace blink
 
 WTF_ALLOW_MOVE_INIT_AND_COMPARE_WITH_MEM_FUNCTIONS(
     blink::WebGLRenderingContextBase::TextureUnitState);
 
 #endif  // WebGLRenderingContextBase_h