Push isEqual/onIsEqual down from GrProcessor to subclasses.

R=joshualitt@google.com

Review URL: https://codereview.chromium.org/654273002
diff --git a/src/gpu/GrAAConvexPathRenderer.cpp b/src/gpu/GrAAConvexPathRenderer.cpp
index 9e16177..00f886c 100644
--- a/src/gpu/GrAAConvexPathRenderer.cpp
+++ b/src/gpu/GrAAConvexPathRenderer.cpp
@@ -584,7 +584,7 @@
                                                         GrShaderVar::kAttribute_TypeModifier))) {
     }
 
-    virtual bool onIsEqual(const GrProcessor& other) const SK_OVERRIDE {
+    virtual bool onIsEqual(const GrGeometryProcessor& other) const SK_OVERRIDE {
         return true;
     }