Implement convertToBlob() in OffscreenCanvas

third_party/WebKit/Source/core/html/canvas/CanvasRenderingContext.h

Index: third_party/WebKit/Source/core/html/canvas/CanvasRenderingContext.h
diff --git a/third_party/WebKit/Source/core/html/canvas/CanvasRenderingContext.h b/third_party/WebKit/Source/core/html/canvas/CanvasRenderingContext.h
index 5da3199bae3be16c86076a0262e3e856357a6e7a..ffdeca2e7e19a6a5dcaa05c22d0ef14285c22be1 100644
--- a/third_party/WebKit/Source/core/html/canvas/CanvasRenderingContext.h
+++ b/third_party/WebKit/Source/core/html/canvas/CanvasRenderingContext.h
@@ -88,6 +88,9 @@ class CORE_EXPORT CanvasRenderingContext
 
   virtual PassRefPtr<Image> getImage(AccelerationHint,
                                      SnapshotReason) const = 0;
+  virtual ImageData* toImageData(SnapshotReason reason) const {

[Justin Novosad, 2016/10/20 16:18:53]

Having this is a good idea. Please create a crbug to refactor around this in a
follow-up CL:
1. Make this method pure virtual (and implement in in all context classes)
2. Augment this method so that it can take the same arguments as
HTMLCanvasElement::toImageData
3. Add a convertToBlob entry to the "SnapshotReason" enum, and add it to the
aprropriate UMA histograms
4. Make HTMLCanvasElement call this method instead using its own toImageData
5. Delete HTMLCanvasElement::toImageData from the code

[xlai (Olivia), 2016/10/20 16:26:27]

Thanks! Creating crbug.com/657870 for record.

+    return nullptr;
+  }
   virtual ContextType getContextType() const = 0;
   virtual bool isAccelerated() const { return false; }
   virtual bool shouldAntialias() const { return false; }