DM: add --serialize

Plus:
  - minor ReplayTask refactoring to share code with SerializeTask
  - move --replay to ReplayTask and --serialize to SerializeTask like WriteTask
  - when --writePath is given, write failures for Replay and Serialize tasks
  - function names have fewer blatant Skia style violations

BUG=
R=bsalomon@google.com

Author: mtklein@google.com

Review URL: https://codereview.chromium.org/32613003

git-svn-id: http://skia.googlecode.com/svn/trunk@11890 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/dm/DMWriteTask.cpp b/dm/DMWriteTask.cpp
index 21a9b55..011b339 100644
--- a/dm/DMWriteTask.cpp
+++ b/dm/DMWriteTask.cpp
@@ -27,7 +27,7 @@
     const SkString dir = SkOSPath::SkPathJoin(root, fConfig.c_str());
     if (!sk_mkdir(root) ||
         !sk_mkdir(dir.c_str())  ||
-        !SkImageEncoder::EncodeFile(png(SkOSPath::SkPathJoin(dir.c_str(), fGmName.c_str())).c_str(),
+        !SkImageEncoder::EncodeFile(Png(SkOSPath::SkPathJoin(dir.c_str(), fGmName.c_str())).c_str(),
                                     fBitmap,
                                     SkImageEncoder::kPNG_Type,
                                     100/*quality*/))