Flakiness dashboard: dump test results json instead of gtest json.

scripts/slave/recipe_modules/test_results/resources/json_results_generator.py

 # Copyright (c) 2015 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 """Generate JSON results from given test results.
 
 Forked from build/scripts/slave/gtest/json_results_generator.py and original
 will be deleted as all tests are moved to swarming.
 """
 
@@ skipping 185 matching lines @@
 
     if modifier == TestResult.NONE:
       return (self.PASS_LABEL, actual)
     if modifier == TestResult.FLAKY:
       return (self.FLAKY_LABEL, actual)
     if modifier == TestResult.FAILS:
       return (self.FAIL_LABEL, actual)
 
   def _write_json(self, json_object, file_path):
     # Specify separators in order to get compact encoding.
-    json_data = json.dumps(json_object, separators=(',', ':'))
+    json_data = json.dumps(json_object, separators=(',', ':'), indent=2)
     json_string = json_data
     if self._file_writer:
       self._file_writer(file_path, json_string)
     else:
       with codecs.open(file_path, 'w', 'utf8') as f:
         f.write(json_string)