Add XferProcessor factory in GrPaint and GrDrawState.

include/gpu/GrInvariantOutput.h

Index: include/gpu/GrInvariantOutput.h
diff --git a/include/gpu/GrInvariantOutput.h b/include/gpu/GrInvariantOutput.h
index 0805ac7933e9c75e66fc03ac86106db00e924ec0..4f61999dcda72fd0e56db7589b784888cd35c74a 100644
--- a/include/gpu/GrInvariantOutput.h
+++ b/include/gpu/GrInvariantOutput.h
@@ -142,6 +142,8 @@ private:
         return (fValidFlags == kRGBA_GrColorComponentFlags && 0xFFFFFFFF == fColor);
     }
 
+    bool isSingleComponent() const { return fIsSingleComponent; }
+
     bool willUseInputColor() const { return fWillUseInputColor; }
     void resetWillUseInputColor() { fWillUseInputColor = true; }