Convert drawPaint to drawRRect in simple cases

src/gpu/GrFixedClip.h

 /*
  * Copyright 2016 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef GrFixedClip_DEFINED
 #define GrFixedClip_DEFINED
 
@@ skipping 21 matching lines @@
         fHasStencilClip = false;
     }
 
     void enableStencilClip() { fHasStencilClip = true; }
     void disableStencilClip() { fHasStencilClip = false; }
 
     bool quickContains(const SkRect&) const final;
     void getConservativeBounds(int width, int height, SkIRect* devResult,
                                bool* isIntersectionOfRects) const final;
 
+    bool isRRect(const SkRect& rtBounds, SkRRect* rr, bool* aa) const override {
+        if (fHasStencilClip) {
+            return false;
+        }
+        if (fScissorState.enabled()) {
+            SkRect rect = SkRect::Make(fScissorState.rect());
+            if (!rect.intersects(rtBounds)) {
+                return false;
+            }
+            rr->setRect(rect);
+            *aa = false;
+            return true;
+        }
+        return false;
+    };
+
 private:
     bool apply(GrContext*, GrDrawContext*, bool useHWAA, bool hasUserStencilSettings,
                GrAppliedClip* out) const final;
 
     GrScissorState   fScissorState;
     bool             fHasStencilClip;
 };
 
 #endif