Implement convertToBlob() in OffscreenCanvas

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 579 matching lines @@
     TraceWrapperMember<WebGLTexture> m_texture2DBinding;
     TraceWrapperMember<WebGLTexture> m_textureCubeMapBinding;
     TraceWrapperMember<WebGLTexture> m_texture3DBinding;
     TraceWrapperMember<WebGLTexture> m_texture2DArrayBinding;
 
     DECLARE_TRACE();
     DECLARE_TRACE_WRAPPERS();
   };
 
   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(ExceptionState&);
 
  protected:
   friend class EXTDisjointTimerQuery;
   friend class WebGLDrawBuffers;
@@ skipping 942 matching lines @@
                   context,
                   context->is3d(),
                   context.is3d());
 
 }  // namespace blink
 
 WTF_ALLOW_MOVE_INIT_AND_COMPARE_WITH_MEM_FUNCTIONS(
     blink::WebGLRenderingContextBase::TextureUnitState);
 
 #endif  // WebGLRenderingContextBase_h