When running DM, write test failures to json.

dm/DMJsonWriter.h

 /*
  * Copyright 2014 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef DMJsonWriter_DEFINED
 #define DMJsonWriter_DEFINED
 
 #include "SkString.h"
+#include "Test.h"
 
 namespace DM {
 
 /**
  *  Class for collecting results from DM and writing to a json file.
  *  All methods are thread-safe.
  */
 class JsonWriter {
 public:
     /**
      *  Info describing a single run.
      */
     struct BitmapResult {
         SkString name;            // E.g. "ninepatch-stretch", "desk-gws_skp"
         SkString config;          //      "gpu", "8888"
         SkString mode;            //      "direct", "default-tilegrid", "pipe"
         SkString sourceType;      //      "GM", "SKP"
         SkString md5;             // In ASCII, so 32 bytes long.
     };
 
     /**
      *  Add a result to the end of the list of results.
      */
     static void AddBitmapResult(const BitmapResult&);
 
     /**
+     *  Add a Failure from a Test.
+     */
+    static void AddTestFailure(const skiatest::Failure&);
+
+    /**
      *  Write all collected results to the file FLAGS_writePath[0]/dm.json.
      */
     static void DumpJson();
 };
 
 } // namespace DM
 #endif // DMJsonWriter_DEFINED