Add nanobench tests for BitmapRegionDecoder

bench/BitmapRegionDecoderBench.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 BitmapRegionDecoderBench_DEFINED
+#define BitmapRegionDecoderBench_DEFINED
+
+#include "Benchmark.h"
+#include "SkBitmapRegionDecoderInterface.h"
+#include "SkData.h"
+#include "SkImageInfo.h"
+#include "SkRefCnt.h"
+#include "SkString.h"
+
+/**
+ *  Benchmark Android's BitmapRegionDecoder for a particular colorType, sampleSize, and subset.
+ *
+ *  fStrategy determines which of various implementations is to be used.
+ *
+ *  nanobench.cpp handles creating benchmarks for interesting scaled subsets.  We strive to test
+ *  on real use cases.
+ */
+class BitmapRegionDecoderBench : public Benchmark {
+public:
+    // Calls encoded->ref()
+    BitmapRegionDecoderBench(const char* basename, SkData* encoded,
+            SkBitmapRegionDecoderInterface::Strategy strategy, SkColorType colorType,
+            uint32_t sampleSize, const SkIRect& subset);
+
+protected:
+    const char* onGetName() override;
+    bool isSuitableFor(Backend backend) override;
+    void onDraw(const int n, SkCanvas* canvas) override;
+    void onPreDraw() override;
+
+private:
+    SkString                                       fName;
+    SkAutoTDelete<SkBitmapRegionDecoderInterface>  fBRD;
+    SkAutoTUnref<SkData>                           fData;
+    const SkBitmapRegionDecoderInterface::Strategy fStrategy;
+    const SkColorType                              fColorType;
+    const uint32_t                                 fSampleSize;
+    const SkIRect                                  fSubset;
+    typedef Benchmark INHERITED;
+};
+#endif // BitmapRegionDecoderBench_DEFINED