Revert of removing GrDrawEffect

include/gpu/GrEffect.h

Index: include/gpu/GrEffect.h
diff --git a/include/gpu/GrEffect.h b/include/gpu/GrEffect.h
index e9259979f0af3946deddf5523ed93d2fd194ecce..102b9d4b961ba89743c8b002426182633ad7b83f 100644
--- a/include/gpu/GrEffect.h
+++ b/include/gpu/GrEffect.h
@@ -130,11 +130,6 @@
         ::operator delete(target, placement);
     }
 
-    /**
-      * Helper for down-casting to a GrEffect subclass
-      */
-    template <typename T> const T& cast() const { return *static_cast<const T*>(this); }
-
 protected:
     /**
      * Subclasses call this from their constructor to register coordinate transformations. The
@@ -158,6 +153,13 @@
         , fWillReadFragmentPosition(false)
         , fWillUseInputColor(true)
         , fRequiresVertexShader(false) {}
+
+    /**
+      * Helper for down-casting to a GrEffect subclass
+      */
+    template <typename T> static const T& CastEffect(const GrEffect& effect) {
+        return *static_cast<const T*>(&effect);
+    }
 
     /**
      * If the effect subclass will read the destination pixel value then it must call this function