Notify listeners on OffScreenCanvas changes

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 4025122739cf070ecf7674ce8b9acca355e2f6e2..83939148c630157bd3523791392c7ba95675fe9e 100644
--- a/third_party/WebKit/Source/core/html/HTMLCanvasElement.h
+++ b/third_party/WebKit/Source/core/html/HTMLCanvasElement.h
@@ -209,6 +209,11 @@ class CORE_EXPORT HTMLCanvasElement final
                                   const ImageBitmapOptions&,
                                   ExceptionState&) override;
 
+  // OffscreenCanvasPlaceholder implementation.
+  void setPlaceholderFrame(RefPtr<StaticBitmapImage>,
+                           WeakPtr<OffscreenCanvasFrameDispatcher>,
+                           RefPtr<WebTaskRunner>,
+                           unsigned resourceId) override;
   DECLARE_VIRTUAL_TRACE();
 
   DECLARE_VIRTUAL_TRACE_WRAPPERS();