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

tools/perf/measurements/record_per_area.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 time
 
 from measurements import smoothness
 from telemetry.page import page_test
+from telemetry.value import improvement_direction
 from telemetry.value import scalar
 
 
 class RecordPerArea(page_test.PageTest):
   def __init__(self, start_wait_time=2):
     super(RecordPerArea, self).__init__('RunPageInteractions', True)
     self._start_wait_time = start_wait_time
 
   def CustomizeBrowserOptions(self, options):
     smoothness.Smoothness.CustomizeBrowserOptions(options)
@@ skipping 30 matching lines @@
 
     all_data = tab.EvaluateJavaScript('window.benchmark_results.results')
     for data in all_data:
       width = data['width']
       height = data['height']
       area = width * height
       time_ms = data['time_ms']
 
       results.AddValue(scalar.ScalarValue(
           results.current_page, 'area_%07d_%dx%d' % (area, width, height),
-          'ms', time_ms))
+          'ms', time_ms, improvement_direction=improvement_direction.DOWN))