Make OffscreenCanvas an EventTarget

third_party/WebKit/Source/modules/webgl/WebGLRenderingContextBase.h

Index: third_party/WebKit/Source/modules/webgl/WebGLRenderingContextBase.h
diff --git a/third_party/WebKit/Source/modules/webgl/WebGLRenderingContextBase.h b/third_party/WebKit/Source/modules/webgl/WebGLRenderingContextBase.h
index b459f9e053d2ce628929f475584f5017ba8f964f..2e1e7d0ce6befceae0f59214d2709bbff2a82d99 100644
--- a/third_party/WebKit/Source/modules/webgl/WebGLRenderingContextBase.h
+++ b/third_party/WebKit/Source/modules/webgl/WebGLRenderingContextBase.h
@@ -591,6 +591,10 @@ class MODULES_EXPORT WebGLRenderingContextBase : public CanvasRenderingContext,
 
   void commit(ScriptState*, ExceptionState&);
 
+  ExecutionContext* getExecutionContext() final {
+    return m_executionContext.get();
+  }
+
  protected:
   friend class EXTDisjointTimerQuery;
   friend class EXTDisjointTimerQueryWebGL2;
@@ -622,6 +626,7 @@ class MODULES_EXPORT WebGLRenderingContextBase : public CanvasRenderingContext,
   WebGLRenderingContextBase(OffscreenCanvas*,
                             std::unique_ptr<WebGraphicsContext3DProvider>,
                             const CanvasContextCreationAttributes&,
+                            ExecutionContext*,
                             unsigned);
   PassRefPtr<DrawingBuffer> createDrawingBuffer(
       std::unique_ptr<WebGraphicsContext3DProvider>,
@@ -1579,6 +1584,7 @@ class MODULES_EXPORT WebGLRenderingContextBase : public CanvasRenderingContext,
                             OffscreenCanvas*,
                             std::unique_ptr<WebGraphicsContext3DProvider>,
                             const CanvasContextCreationAttributes&,
+                            ExecutionContext*,
                             unsigned);
   static std::unique_ptr<WebGraphicsContext3DProvider>
   createContextProviderInternal(HTMLCanvasElement*,
@@ -1590,6 +1596,8 @@ class MODULES_EXPORT WebGLRenderingContextBase : public CanvasRenderingContext,
 
   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(); }
 };