Bench baseline for mostly 0 image.

Add a baseline for decoding a mostly 0 image. This is in advance of
https://codereview.chromium.org/24269006/ which provides an option to
skip writing those 0s (as part of BUG=skia:1661). On my Nexus 4, the
benchmark does not slow down after that change.

As suggested in https://codereview.chromium.org/24269006/ add a
resourcePath flag to bench. Will require a change in buildbot in order
to actually use the flag.

Add an image used by the test.

Until https://codereview.chromium.org/24448002 is submitted,
the test will not actually be run by the bots (since it
won't know where to find the file).

BUG=skia:1661
R=djsollen@google.com, mtklein@google.com

Review URL: https://codereview.chromium.org/24440002

git-svn-id: http://skia.googlecode.com/svn/trunk@11461 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/bench/SkBenchmark.h b/bench/SkBenchmark.h
index 811a1db..ec40077 100644
--- a/bench/SkBenchmark.h
+++ b/bench/SkBenchmark.h
@@ -10,6 +10,7 @@
 
 #include "SkRefCnt.h"
 #include "SkPoint.h"
+#include "SkString.h"
 #include "SkTRegistry.h"
 
 #define DEF_BENCH(code) \
@@ -106,6 +107,10 @@
     //   for (int i = 0; i < this->getLoops(); i++) { <work here> }
     int getLoops() const { return fLoops; }
 
+    static void SetResourcePath(const char* resPath) { gResourcePath.set(resPath); }
+
+    static SkString& GetResourcePath() { return gResourcePath; }
+
 protected:
     virtual void setupPaint(SkPaint* paint);
 
@@ -125,6 +130,7 @@
     SkTriState::State  fDither;
     uint32_t    fOrMask, fClearMask;
     int fLoops;
+    static  SkString gResourcePath;
 
     typedef SkRefCnt INHERITED;
 };