Add GM that directly tests GrRRectEffect and add inverse fill version of effect.

src/gpu/effects/GrRRectEffect.h

 /*
  * Copyright 2014 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef GrRRectEffect_DEFINED
 #define GrRRectEffect_DEFINED
 
 #include "GrTypes.h"
 
 class GrEffectRef;
 class SkRRect;
 
 namespace GrRRectEffect {
+    enum EdgeType {
+        kFillAA_EdgeType,
+        kInverseFillAA_EdgeType,
+        
+        kLastEdgeType = kInverseFillAA_EdgeType,
+    };
+    
+    static const int kEdgeTypeCnt = kLastEdgeType + 1;
+
     /**
      * Creates an effect that performs anti-aliased clipping against a SkRRect. It doesn't support
      * all varieties of SkRRect so the caller must check for a NULL return.
      */
-    GrEffectRef* Create(const SkRRect&);
+    GrEffectRef* Create(EdgeType, const SkRRect&);
 };
 
 #endif