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/GrMatrixConvolutionEffect.cpp b/src/gpu/effects/GrMatrixConvolutionEffect.cpp
index 07b4851..1f98267 100644
--- a/src/gpu/effects/GrMatrixConvolutionEffect.cpp
+++ b/src/gpu/effects/GrMatrixConvolutionEffect.cpp
@@ -176,7 +176,7 @@
     return GrTBackendFragmentProcessorFactory<GrMatrixConvolutionEffect>::getInstance();
 }
 
-bool GrMatrixConvolutionEffect::onIsEqual(const GrProcessor& sBase) const {
+bool GrMatrixConvolutionEffect::onIsEqual(const GrFragmentProcessor& sBase) const {
     const GrMatrixConvolutionEffect& s = sBase.cast<GrMatrixConvolutionEffect>();
     return this->texture(0) == s.texture(0) &&
            fKernelSize == s.kernelSize() &&