Create fragment processor for performing input color blend with child processor

include/gpu/effects/GrXfermodeFragmentProcessor.h

Index: include/gpu/effects/GrXfermodeFragmentProcessor.h
diff --git a/include/gpu/effects/GrXfermodeFragmentProcessor.h b/include/gpu/effects/GrXfermodeFragmentProcessor.h
index d93b400b8bf29309cdfb98359d1c3156d221b1ad..e2d1c0a544326c414ad861ca97d89b74a184f70d 100644
--- a/include/gpu/effects/GrXfermodeFragmentProcessor.h
+++ b/include/gpu/effects/GrXfermodeFragmentProcessor.h
@@ -13,6 +13,16 @@
 class GrFragmentProcessor;
 
 namespace GrXfermodeFragmentProcessor {
+    /** The color input to the returned processor is treated as the src and the passed in processor
+        is the dst. */
+    const GrFragmentProcessor* CreateFromDstProcessor(const GrFragmentProcessor* dst,
+                                                      SkXfermode::Mode mode);
+
+    /** The color input to the returned processor is treated as the dst and the passed in processor
+        is the src. */
+    const GrFragmentProcessor* CreateFromSrcProcessor(const GrFragmentProcessor* src,
+                                                      SkXfermode::Mode mode);
+
     const GrFragmentProcessor* CreateFromTwoProcessors(const GrFragmentProcessor* src,
                                                        const GrFragmentProcessor* dst,
                                                        SkXfermode::Mode mode);