Added support for improvement_direction to relevant values, which is propogated to chartjson.

tools/perf/benchmarks/dom_perf.py

 # Copyright 2013 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.
 
 import json
 import math
 import os
 
 from telemetry import benchmark
 from telemetry import page as page_module
@@ skipping 33 matching lines @@
       def _IsDone():
         return tab.GetCookieByName('__domperf_finished') == '1'
       util.WaitFor(_IsDone, 600)
 
       data = json.loads(tab.EvaluateJavaScript('__domperf_result'))
       for suite in data['BenchmarkSuites']:
         # Skip benchmarks that we didn't actually run this time around.
         if len(suite['Benchmarks']) or suite['score']:
           results.AddValue(scalar.ScalarValue(
               results.current_page, '%s.%s' % (suite['name'], SCORE_TRACE_NAME),
-              SCORE_UNIT, suite['score'], important=False))
+              SCORE_UNIT, suite['score'], important=False,
+              higher_is_better=True))

[tonyg, 2014/12/18 17:31:35]

For anything that is summarizable into a numeric value, I don't think we should
leave this parameter optional. There's no good way to check that we've
considered all of the cases in this CL and in the future, folks might forget to
specify.

That being said, we also don't want to have a naked boolean in the API. A couple
of ideas are:
- We could assert that the field is passed by name and continue to use a bool
- We could assert a different type besides bool that has a more readable name

     finally:
       tab.EvaluateJavaScript('document.cookie = "__domperf_finished=0"')
 
   def DidRunTest(self, browser, results):
     # Now give the geometric mean as the total for the combined runs.
     combined = merge_values.MergeLikeValuesFromDifferentPages(
         results.all_page_specific_values,
         group_by_name_suffix=True)
     combined_score = [x for x in combined if x.name == SCORE_TRACE_NAME][0]
     total = _GeometricMean(combined_score.values)
@@ skipping 23 matching lines @@
       'Events',
       'Get+Elements',
       'GridSort',
       'Template'
     ]
     ps = page_set.PageSet(file_path=dom_perf_dir)
     for param in run_params:
       ps.AddUserStory(page_module.Page(
           'file://run.html?reportInJS=1&run=%s' % param, ps, ps.base_dir))
     return ps