add SkPictureUtils::GatherPixelRefs()
Review URL: https://codereview.appspot.com/6845106

git-svn-id: http://skia.googlecode.com/svn/trunk@6615 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/tools/bench_pictures_main.cpp b/tools/bench_pictures_main.cpp
index 409439e..c1d0e1c 100644
--- a/tools/bench_pictures_main.cpp
+++ b/tools/bench_pictures_main.cpp
@@ -413,6 +413,8 @@
             } else if (0 == strcmp(*argv, "playbackCreation")) {
                 renderer.reset(SkNEW(sk_tools::PlaybackCreationRenderer));
                 gridSupported = true;
+            } else if (0 == strcmp(*argv, "gatherPixelRefs")) {
+                renderer.reset(sk_tools::CreateGatherPixelRefsRenderer());
             } else {
                 SkString err;
                 err.printf("%s is not a valid mode for --mode\n", *argv);