Small fix for visualbench

tools/VisualBench/VisualBench.cpp

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  *
  */
 
 #include "VisualBench.h"
 
@@ skipping 87 matching lines @@
         INHERITED::detach();
         return false;
     }
 
     this->setVsync(false);
     this->resetContext();
     return true;
 }
 
 void VisualBench::resetContext() {
+    fSurface.reset(NULL);
+
     fInterface.reset(GrGLCreateNativeInterface());
     SkASSERT(fInterface);
 
     // setup contexts
     fContext.reset(GrContext::Create(kOpenGL_GrBackend, (GrBackendContext)fInterface.get()));
     SkASSERT(fContext);
 
     // setup rendertargets
     this->setupRenderTarget();
 }
@@ skipping 155 matching lines @@
 
 void application_term() {
     SkEvent::Term();
     SkGraphics::Term();
 }
 
 SkOSWindow* create_sk_window(void* hwnd, int argc, char** argv) {
     return new VisualBench(hwnd, argc, argv);
 }