[wrapper-tracing] WebGL and friends: Add write barriers

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

Index: third_party/WebKit/Source/core/html/HTMLCanvasElement.h
diff --git a/third_party/WebKit/Source/core/html/HTMLCanvasElement.h b/third_party/WebKit/Source/core/html/HTMLCanvasElement.h
index 6488ffc2c4748b53d420ea742c9a2e0772ac29f6..2ee49a549bb0307b9db9a811d55fb964357d3c81 100644
--- a/third_party/WebKit/Source/core/html/HTMLCanvasElement.h
+++ b/third_party/WebKit/Source/core/html/HTMLCanvasElement.h
@@ -29,6 +29,7 @@
 #define HTMLCanvasElement_h
 
 #include "bindings/core/v8/ScriptValue.h"
+#include "bindings/core/v8/ScriptWrappableVisitor.h"
 #include "core/CoreExport.h"
 #include "core/dom/ContextLifecycleObserver.h"
 #include "core/dom/DOMTypedArray.h"
@@ -291,7 +292,7 @@ class CORE_EXPORT HTMLCanvasElement final : public HTMLElement,
 
   IntSize m_size;
 
-  Member<CanvasRenderingContext> m_context;
+  TraceWrapperMember<CanvasRenderingContext> m_context;
 
   bool m_ignoreReset;
   FloatRect m_dirtyRect;