Remove default implementation of GrEffect::isEqual. Make GrSingleTextureEffect abstract.
Review URL: https://codereview.appspot.com/7142049

git-svn-id: http://skia.googlecode.com/svn/trunk@7254 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/src/gpu/effects/GrConvolutionEffect.h b/src/gpu/effects/GrConvolutionEffect.h
index 4f0c9ec..944d34f 100644
--- a/src/gpu/effects/GrConvolutionEffect.h
+++ b/src/gpu/effects/GrConvolutionEffect.h
@@ -51,7 +51,12 @@
     typedef GrGLConvolutionEffect GLEffect;
 
     virtual const GrBackendEffectFactory& getFactory() const SK_OVERRIDE;
-    virtual bool isEqual(const GrEffect&) const SK_OVERRIDE;
+
+    virtual void getConstantColorComponents(GrColor* color, uint32_t* validFlags) const {
+        // If the texture was opaque we could know that the output color if we knew the sum of the
+        // kernel values.
+        *validFlags = 0;
+    }
 
     enum {
         // This was decided based on the min allowed value for the max texture
@@ -77,6 +82,8 @@
                         int halfWidth,
                         float gaussianSigma);
 
+    virtual bool onIsEqual(const GrEffect&) const SK_OVERRIDE;
+
     GR_DECLARE_EFFECT_TEST;
 
     typedef Gr1DKernelEffect INHERITED;