Implement SkGLContext swapBuffers with fence syncs

bench/nanobenchAndroid.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 nanobenchAndroid_DEFINED
 #define nanobenchAndroid_DEFINED
 
 #include "SkAndroidSDKCanvas.h"
 #include "SkHwuiRenderer.h"
 
 #include "nanobench.h"
 
 struct HWUITarget : public Target {
     explicit HWUITarget(const Config& c, Benchmark* bench);
 
     SkHwuiRenderer renderer;
     SkAndroidSDKCanvas fc;
 
     void setup() override;
     SkCanvas* beginTiming(SkCanvas* canvas) override;
     void endTiming() override;
     void fence() override;
-    bool needsFrameTiming() const override;
+    bool needsFrameTiming(int* frameLag) const override;
 
     bool init(SkImageInfo info, Benchmark* bench) override;
     bool capturePixels(SkBitmap* bmp) override;
 };
 
 #endif  // nanobenchAndroid_DEFINED