Add option to draw wireframe batch bounds

src/gpu/batches/GrClearBatch.h

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef GrClearBatch_DEFINED
 #define GrClearBatch_DEFINED
 
@@ skipping 10 matching lines @@
         : INHERITED(ClassID())
         , fRect(rect)
         , fColor(color)
         , fRenderTarget(rt) {
         fBounds = SkRect::Make(rect);
     }
 
     const char* name() const override { return "Clear"; }
 
     uint32_t renderTargetUniqueID() const override { return fRenderTarget.get()->getUniqueID(); }
+    GrRenderTarget* renderTarget() const override { return fRenderTarget.get(); }
 
     SkString dumpInfo() const override {
         SkString string;
         string.printf("Color: 0x%08x, Rect [L: %d, T: %d, R: %d, B: %d], RT: %d",
                       fColor, fRect.fLeft, fRect.fTop, fRect.fRight, fRect.fBottom,
                       fRenderTarget.get()->getUniqueID());
         return string;
     }
 
 private:
@@ skipping 23 matching lines @@
         : INHERITED(ClassID())
         , fRect(rect)
         , fInsideClip(insideClip)
         , fRenderTarget(rt) {
         fBounds = SkRect::Make(rect);
     }
 
     const char* name() const override { return "ClearStencilClip"; }
 
     uint32_t renderTargetUniqueID() const override { return fRenderTarget.get()->getUniqueID(); }
+    GrRenderTarget* renderTarget() const override { return fRenderTarget.get(); }
 
     SkString dumpInfo() const override {
         SkString string;
         string.printf("Rect [L: %d, T: %d, R: %d, B: %d], IC: %d, RT: 0x%p",
                       fRect.fLeft, fRect.fTop, fRect.fRight, fRect.fBottom, fInsideClip,
                       fRenderTarget.get());
         return string;
     }
 
 private:
     bool onCombineIfPossible(GrBatch* t, const GrCaps& caps) override { return false; }
 
     void onPrepare(GrBatchFlushState*) override {}
 
     void onDraw(GrBatchFlushState* state) override {
         state->gpu()->clearStencilClip(fRect, fInsideClip, fRenderTarget.get());
     }
 
     SkIRect                                                 fRect;
     bool                                                    fInsideClip;
     GrPendingIOResource<GrRenderTarget, kWrite_GrIOType>    fRenderTarget;
 
     typedef GrBatch INHERITED;
 };
 
 #endif