Adding new benchmark to test image decoding performance.

bench/SKDBench.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.
+ */
+
+#include "Benchmark.h"
+#include "SkImageDecoder.h"

[scroggo, 2015/02/11 19:38:10]

I don't think you need to include SkImageDecoder.h, but you should include
others, e.g.

SkString.h
SkImageInfo.h

[msarett, 2015/02/11 21:57:01]

Done.

+
+/*
+ *
+ * This benchmark is designed to test the performance of image decoding.
+ * It is invoked from the nanobench.cpp file.
+ *
+ */
+class SKDBench : public Benchmark {

[mtklein, 2015/02/11 19:15:36]

Let's call it DecodingBench?  D is a little vague, and we don't really need the
Sk.  This isn't part of the Skia library (no one outside of tools we write is
expected to link in one of these).

(If you were modeling it of SKPBench, I can see how that's confusing.  We write
SkPictures to files with an .skp extension, so SKPBench is sort of the natural
name for that.)

[scroggo, 2015/02/11 19:38:10]

+1

I also think we should remove the existing DecodeBench and ImageDecodeBench.

[msarett, 2015/02/11 21:57:01]

Done.

[msarett, 2015/02/11 21:57:01]

Done.

+public:
+    SKDBench(const char* name, SkString path, SkColorType colorType);

[scroggo, 2015/02/11 19:38:10]

What is "name"? It looks like we always use "SKD"?

[msarett, 2015/02/11 21:57:01]

Done.

+
+protected:
+    const char* onGetName() SK_OVERRIDE;
+    bool isSuitableFor(Backend backend) SK_OVERRIDE;
+    void onDraw(const int n, SkCanvas* canvas) SK_OVERRIDE;
+    
+private:
+    SkString fName;
+    SkString fPath;
+    SkColorType fColorType;
+    typedef Benchmark INHERITED;
+};