[SkiaBenchmarkingExtension] Add draw command timing info.

skia/ext/benchmarking_canvas.h

Index: skia/ext/benchmarking_canvas.h
diff --git a/skia/ext/benchmarking_canvas.h b/skia/ext/benchmarking_canvas.h
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+// Copyright (c) 2013 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef SKIA_EXT_BENCHMARKING_CANVAS_H_
+#define SKIA_EXT_BENCHMARKING_CANVAS_H_
+
+#include "base/compiler_specific.h"
+#include "skia/ext/refptr.h"
+#include "third_party/skia/include/utils/SkNWayCanvas.h"
+#include "third_party/skia/src/utils/debugger/SkDebugCanvas.h"
+
+namespace skia {
+
+class TimingCanvas;
+
+class SK_API BenchmarkingCanvas : public SkNWayCanvas {
+public:
+  BenchmarkingCanvas(int width, int height);
+  virtual ~BenchmarkingCanvas();
+
+  // Returns the number of draw commands executed on this canvas.
+  size_t CommandCount() const;
+
+  // Get draw command info for a given index.
+  SkDrawCommand* GetCommand(size_t index);
+
+  // Return the recorded render time (milliseconds) for a draw command index.
+  double GetTime(size_t index);
+
+private:
+  // In order to avoid introducing a Skia version dependency, this
+  // implementation dispatches draw commands in lock-step to two distinct
+  // canvases:
+  //   * a SkDebugCanvas used for gathering command info and tracking
+  //     the current command index
+  //   * a SkiaTimingCanvas used for measuring raster paint times (and relying
+  //     on the former for tracking the current command index).
+  //
+  // This way, if the SkCanvas API is extended, we don't need to worry about
+  // updating content::SkiaTimingCanvas to accurately override all new methods
+  // (to avoid timing info indices from getting out of sync), as SkDebugCanvas
+  // already does that for us.
+
+  skia::RefPtr<SkDebugCanvas> debug_canvas_;
+  skia::RefPtr<TimingCanvas> timing_canvas_;
+};
+
+}
+#endif // SKIA_EXT_BENCHMARKING_CANVAS_H