Add some plumbing for the color management of canvases

third_party/WebKit/Source/modules/canvas2d/CanvasRenderingContext2D.cpp

Index: third_party/WebKit/Source/modules/canvas2d/CanvasRenderingContext2D.cpp
diff --git a/third_party/WebKit/Source/modules/canvas2d/CanvasRenderingContext2D.cpp b/third_party/WebKit/Source/modules/canvas2d/CanvasRenderingContext2D.cpp
index fac95dfa3865c18527a4643fc013bd7dc6d5c1e9..1b3e420e195831e8eb2dd4c3db45d9be1ae9f5c2 100644
--- a/third_party/WebKit/Source/modules/canvas2d/CanvasRenderingContext2D.cpp
+++ b/third_party/WebKit/Source/modules/canvas2d/CanvasRenderingContext2D.cpp
@@ -109,7 +109,7 @@ private:
 };
 
 CanvasRenderingContext2D::CanvasRenderingContext2D(HTMLCanvasElement* canvas, const CanvasContextCreationAttributes& attrs, Document& document)
-    : CanvasRenderingContext(canvas)
+    : CanvasRenderingContext(canvas, nullptr, attrs.colorSpace())
     , m_hasAlpha(attrs.alpha())
     , m_contextLostMode(NotLostContext)
     , m_contextRestorable(true)
@@ -911,6 +911,7 @@ WebLayer* CanvasRenderingContext2D::platformLayer() const
 void CanvasRenderingContext2D::getContextAttributes(Canvas2DContextAttributes& attrs) const
 {
     attrs.setAlpha(m_hasAlpha);
+    attrs.setColorSpace(colorSpaceAsString());

[Stephen White, 2016/08/11 20:41:27]

Shouldn't the base class be responsible for this? (We'll have to virtualize
getContextAttributes() and call the base class from here, but that seems like
that would be the most scalable way to do it.)

[Justin Novosad, 2016/08/12 17:40:18]

Nope.  The base class is in core, so it can't know about
Canvas2DContextAttributes, it only knows about CanvasContextCreationAttributes
(the non-specific flavor of the attributes).

 }
 
 void CanvasRenderingContext2D::drawFocusIfNeeded(Element* element)