Make CSSStyleImageValue a member of CanvasImageSource.

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

Index: third_party/WebKit/Source/core/html/canvas/CanvasImageSource.h
diff --git a/third_party/WebKit/Source/core/html/canvas/CanvasImageSource.h b/third_party/WebKit/Source/core/html/canvas/CanvasImageSource.h
index f38c8e22c88062cad45ce419336adf2364cbff3b..c80d41dfec477db140c94b3897de4e381516311b 100644
--- a/third_party/WebKit/Source/core/html/canvas/CanvasImageSource.h
+++ b/third_party/WebKit/Source/core/html/canvas/CanvasImageSource.h
@@ -34,6 +34,8 @@
 namespace blink {
 
 class Image;
+class FloatRect;
+class FloatSize;

[Justin Novosad, 2016/09/28 15:41:58]

Why are these forward declarations needed?

[Gleb Lanbin, 2016/09/28 16:58:22]

deleted but I think we need these declarations to avoid hidden dependencies

 class SecurityOrigin;
 
 enum SourceImageStatus {
@@ -54,6 +56,7 @@ public:
     // another canvas, which may not be already tainted.
     virtual bool wouldTaintOrigin(SecurityOrigin* destinationSecurityOrigin) const = 0;
 
+    virtual bool isCSSImageValue() const { return false; }
     virtual bool isVideoElement() const { return false; }
     virtual bool isCanvasElement() const { return false; }
     virtual bool isSVGSource() const { return false; }