Add UMA to HTMLCanvasElement to track image formats usage of toDataURL/toBlob

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

 /*
  * Copyright (C) 2004, 2006, 2009, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2007 Alp Toker <alp@atoker.com>
  * Copyright (C) 2010 Torch Mobile (Beijing) Co. Ltd. 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.
@@ skipping 80 matching lines @@
         setHeight(newSize.height());
         m_ignoreReset = false;
         reset();
     }
 
     // Called by Document::getCSSCanvasContext as well as above getContext().
     CanvasRenderingContext* getCanvasRenderingContext(const String&, const CanvasContextCreationAttributes&);
 
     bool isPaintable() const;
 
-    static String toEncodingMimeType(const String& mimeType);
+    static String toEncodingMimeType(const String& mimeType, const String& callFunctionName);
     String toDataURL(const String& mimeType, const ScriptValue& qualityArgument, ExceptionState&) const;
     String toDataURL(const String& mimeType, ExceptionState& exceptionState) const { return toDataURL(mimeType, ScriptValue(), exceptionState); }
 
     void toBlob(BlobCallback*, const String& mimeType, const ScriptValue& qualityArgument, ExceptionState&);
     void toBlob(BlobCallback* callback, const String& mimeType, ExceptionState& exceptionState) { return toBlob(callback, mimeType, ScriptValue(), exceptionState); }
 
     // Used for canvas capture.
     void addListener(CanvasDrawListener*);
     void removeListener(CanvasDrawListener*);
 
@@ skipping 66 matching lines @@
     static void registerRenderingContextFactory(PassOwnPtr<CanvasRenderingContextFactory>);
     void updateExternallyAllocatedMemory() const;
 
     void styleDidChange(const ComputedStyle* oldStyle, const ComputedStyle& newStyle);
 
     void notifyListenersCanvasChanged();
 
     bool isSupportedInteractiveCanvasFallback(const Element&);
     std::pair<Element*, String> getControlAndIdIfHitRegionExists(const LayoutPoint&);
 
+    enum CanvasReturnImageFormat {

[Justin Novosad, 2016/03/22 15:09:04]

This does not need to be in the header. Also, why "CanvasReturn"?  IMHO, a mor
appropriate name would be "RequestedImageMimeType"

+        Png = 0,

[Justin Novosad, 2016/03/22 15:09:04]

enum members should have the enum name as a prefix. Something like
RequestedImageMimeTypeJpeg

+        Jpeg = 1,
+        Webp = 2,
+        Gif = 3,
+        Bmp = 4,
+        Ico = 5,
+        Tiff = 6,
+        NumberOfImageFormats

[Justin Novosad, 2016/03/22 15:09:04]

You should add an "Unknown" value

+    };
+
 protected:
     void didMoveToNewDocument(Document& oldDocument) override;
 
 private:
     explicit HTMLCanvasElement(Document&);
 
     using ContextFactoryVector = Vector<OwnPtr<CanvasRenderingContextFactory>>;
     static ContextFactoryVector& renderingContextFactories();
     static CanvasRenderingContextFactory* getRenderingContextFactory(int);
 
@@ skipping 34 matching lines @@
     mutable bool m_didFailToCreateImageBuffer;
     bool m_imageBufferIsClear;
     OwnPtr<ImageBuffer> m_imageBuffer;
 
     mutable RefPtr<Image> m_copiedImage; // FIXME: This is temporary for platforms that have to copy the image buffer to render (and for CSSCanvasValue).
 };
 
 } // namespace blink
 
 #endif // HTMLCanvasElement_h