Create fragment processor for performing input color blend with child processor

include/gpu/effects/GrCustomXfermode.h

Index: include/gpu/effects/GrCustomXfermode.h
diff --git a/include/gpu/effects/GrCustomXfermode.h b/include/gpu/effects/GrCustomXfermode.h
index 557397077e2f0b5968e0ea889a8255c1879e4446..bcbd5833ca8741a02295b9ab0e0f83f6d3178bd2 100644
--- a/include/gpu/effects/GrCustomXfermode.h
+++ b/include/gpu/effects/GrCustomXfermode.h
@@ -10,21 +10,14 @@
 
 #include "SkXfermode.h"
 
-class GrFragmentProcessor;
 class GrTexture;
 
 /**
  * Custom Xfer modes are used for blending when the blend mode cannot be represented using blend
- * coefficients. It is assumed that all blending is done within the processors' emit code. For each
- * blend mode there should be a matching fragment processor (used when blending with a background
- * texture) and xfer processor.
+ * coefficients.
  */
 namespace GrCustomXfermode {
-    bool IsSupportedMode(SkXfermode::Mode mode); 
-
-    GrFragmentProcessor* CreateFP(GrProcessorDataManager*, SkXfermode::Mode mode,
-                                  GrTexture* background);
-
+    bool IsSupportedMode(SkXfermode::Mode mode);
     GrXPFactory* CreateXPFactory(SkXfermode::Mode mode);
 };