Make OffscreenCanvas an EventTarget

third_party/WebKit/Source/core/offscreencanvas/OffscreenCanvas.h

Index: third_party/WebKit/Source/core/offscreencanvas/OffscreenCanvas.h
diff --git a/third_party/WebKit/Source/core/offscreencanvas/OffscreenCanvas.h b/third_party/WebKit/Source/core/offscreencanvas/OffscreenCanvas.h
index 656b4dd24c7d6d2a11270afbd14339a5fdc15ee2..b455beb9b1427d7491c5fb1a39daa59aa5305328 100644
--- a/third_party/WebKit/Source/core/offscreencanvas/OffscreenCanvas.h
+++ b/third_party/WebKit/Source/core/offscreencanvas/OffscreenCanvas.h
@@ -8,6 +8,7 @@
 #include "bindings/core/v8/ScriptPromise.h"
 #include "bindings/core/v8/ScriptState.h"
 #include "bindings/core/v8/ScriptWrappable.h"
+#include "core/events/EventTarget.h"
 #include "core/html/HTMLCanvasElement.h"
 #include "core/html/canvas/CanvasImageSource.h"
 #include "core/offscreencanvas/ImageEncodeOptions.h"
@@ -25,14 +26,13 @@ class
 typedef OffscreenCanvasRenderingContext2DOrWebGLRenderingContextOrWebGL2RenderingContext
     OffscreenRenderingContext;
 
-class CORE_EXPORT OffscreenCanvas final
-    : public GarbageCollectedFinalized<OffscreenCanvas>,
-      public ScriptWrappable,
-      public CanvasImageSource {
+class CORE_EXPORT OffscreenCanvas final : public EventTargetWithInlineData,
+                                          public CanvasImageSource {
   DEFINE_WRAPPERTYPEINFO();
 
  public:
   static OffscreenCanvas* create(unsigned width, unsigned height);
+  ~OffscreenCanvas() override {}
 
   // IDL attributes
   unsigned width() const { return m_size.width(); }
@@ -84,6 +84,18 @@ class CORE_EXPORT OffscreenCanvas final
   uint64_t nonceHigh() const { return m_nonceHigh; }
   uint64_t nonceLow() const { return m_nonceLow; }
 
+  void setExecutionContext(ExecutionContext* context) {
+    m_executionContext = context;
+  }
+
+  // EventTarget implementation
+  const AtomicString& interfaceName() const final {
+    return EventTargetNames::OffscreenCanvas;
+  }
+  ExecutionContext* getExecutionContext() const {
+    return m_executionContext.get();
+  }
+
   // CanvasImageSource implementation
   PassRefPtr<Image> getSourceImageForCanvas(SourceImageStatus*,
                                             AccelerationHint,
@@ -110,6 +122,7 @@ class CORE_EXPORT OffscreenCanvas final
   static CanvasRenderingContextFactory* getRenderingContextFactory(int);
 
   Member<CanvasRenderingContext> m_context;
+  Member<ExecutionContext> m_executionContext;

[Justin Novosad, 2016/11/14 19:45:08]

Nit: This reference is not need for lifetime management purposes, so you could
make this a WeakMember, then you won't have to trace into it.

[xidachen, 2016/11/14 19:56:38]

Changed to WeakMember. But still need to trace it, otherwise compiler complains:
[blink-gc] Class 'OffscreenCanvas' has untraced fields that require tracing.

   int m_canvasId = -1;  // DOMNodeIds starts from 0, using -1 to indicate no
                         // associated canvas element.