Add nanobench tests for BitmapRegionDecoder

bench/CodecBenchPriv.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 CodecBenchPriv_DEFINED
+#define CodecBenchPriv_DEFINED
+
+#include "SkImageInfo.h"
+
+inline const char* color_type_to_str(SkColorType colorType) {
+    switch (colorType) {
+        case kN32_SkColorType:
+            return "N32";
+        case kRGB_565_SkColorType:
+            return "565";
+        case kGray_8_SkColorType:
+            return "Gray8";
+        case kIndex_8_SkColorType:
+            return "Index8";
+        case kAlpha_8_SkColorType:
+            return "Alpha8";
+        default:
+            return "Unknown";
+    }
+}
+
+#endif // CodecBenchPriv_DEFINED