DM: add --writePath

For fun, make the output prettier, hiding ", N failures" unless there is one.

BUG=
R=bsalomon@google.com

Review URL: https://codereview.chromium.org/29293003

git-svn-id: http://skia.googlecode.com/svn/trunk@11867 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/dm/DMReplayTask.cpp b/dm/DMReplayTask.cpp
index e5f392c..0d6780e 100644
--- a/dm/DMReplayTask.cpp
+++ b/dm/DMReplayTask.cpp
@@ -51,4 +51,4 @@
            fGM->getFlags() & skiagm::GM::kSkipPicture_Flag;
 }
 
-}  // namespace
+}  // namespace DM