Add viewer mode to VisualBench.

tools/VisualBench/VisualBench.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 VisualBench_DEFINED
 #define VisualBench_DEFINED
@@ skipping 15 matching lines @@
 /*
  * A Visual benchmarking tool for gpu benchmarking
  */
 class VisualBench : public SkOSWindow {
 public:
     VisualBench(void* hwnd, int argc, char** argv);
     ~VisualBench() override;
 
     void reset() { this->resetContext(); }
 
+    void clear(SkCanvas* canvas, SkColor color, int frames);
+
 protected:
     SkSurface* createSurface() override;
 
     void draw(SkCanvas* canvas) override;
 
     void onSizeChange() override;
 
 private:
     void setTitle();
     bool setupBackend();
     void resetContext();
     void setupRenderTarget();
     bool onHandleChar(SkUnichar unichar) override;
 
     // support framework
     SkAutoTDelete<VisualModule> fModule;
     SkAutoTUnref<SkSurface> fSurface;
     SkAutoTUnref<GrContext> fContext;
     SkAutoTUnref<GrRenderTarget> fRenderTarget;
     AttachmentInfo fAttachmentInfo;
     SkAutoTUnref<const GrGLInterface> fInterface;
 
     typedef SkOSWindow INHERITED;
 };
 
 #endif