Push isEqual/onIsEqual down from GrProcessor to subclasses.

R=joshualitt@google.com

Review URL: https://codereview.chromium.org/654273002
diff --git a/src/gpu/effects/GrTextureDomain.cpp b/src/gpu/effects/GrTextureDomain.cpp
index 596415e..647aed4 100644
--- a/src/gpu/effects/GrTextureDomain.cpp
+++ b/src/gpu/effects/GrTextureDomain.cpp
@@ -263,7 +263,7 @@
     return GrTBackendFragmentProcessorFactory<GrTextureDomainEffect>::getInstance();
 }
 
-bool GrTextureDomainEffect::onIsEqual(const GrProcessor& sBase) const {
+bool GrTextureDomainEffect::onIsEqual(const GrFragmentProcessor& sBase) const {
     const GrTextureDomainEffect& s = sBase.cast<GrTextureDomainEffect>();
     return this->hasSameTextureParamsMatrixAndSourceCoords(s) &&
            this->fTextureDomain == s.fTextureDomain;