Push isEqual/onIsEqual down from GrProcessor to subclasses.

src/core/SkXfermode.cpp

Index: src/core/SkXfermode.cpp
diff --git a/src/core/SkXfermode.cpp b/src/core/SkXfermode.cpp
index e115f6fd98ba5ea5cd83d5400683c0f93f190421..c131842165600e6d24ff1eb8c674e4c372879a10 100644
--- a/src/core/SkXfermode.cpp
+++ b/src/core/SkXfermode.cpp
@@ -1206,7 +1206,7 @@ private:
             this->setWillReadDstColor();
         }
     }
-    virtual bool onIsEqual(const GrProcessor& other) const SK_OVERRIDE {
+    virtual bool onIsEqual(const GrFragmentProcessor& other) const SK_OVERRIDE {
         const XferEffect& s = other.cast<XferEffect>();
         return fMode == s.fMode &&
                fBackgroundAccess.getTexture() == s.fBackgroundAccess.getTexture();