Flush GrContext between benchmark draw loops

tools/VisualBench/VisualSKPBench.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 "VisualSKPBench.h"
 
+#if SK_SUPPORT_GPU
+#include "GrContext.h"
+#endif
+
 VisualSKPBench::VisualSKPBench(const char* name, const SkPicture* pic)
     : fPic(SkRef(pic))
     , fName(name) {
     fUniqueName.printf("%s", name);
 }
 
 const char* VisualSKPBench::onGetName() {
     return fName.c_str();
 }
 
 const char* VisualSKPBench::onGetUniqueName() {
     return fUniqueName.c_str();
 }
 
 bool VisualSKPBench::isSuitableFor(Backend backend) {
     return backend != kNonRendering_Backend;
 }
 
 void VisualSKPBench::onDraw(int loops, SkCanvas* canvas) {
     for (int i = 0; i < loops; i++) {
         canvas->drawPicture(fPic);
+#if SK_SUPPORT_GPU
+        // Ensure the GrContext doesn't batch across draw loops.
+        if (GrContext* context = canvas->getGrContext()) {
+            context->flush();
+        }
+#endif
     }
 }