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

tools/perf/measurements/oilpan_gc_times.py

Index: tools/perf/measurements/oilpan_gc_times.py
diff --git a/tools/perf/measurements/oilpan_gc_times.py b/tools/perf/measurements/oilpan_gc_times.py
index 3e7fd435329724b5f1d885df76b547d02e06b304..8e6f74b5810e0b083c67c9308e64e561a64f5209 100644
--- a/tools/perf/measurements/oilpan_gc_times.py
+++ b/tools/perf/measurements/oilpan_gc_times.py
@@ -12,6 +12,7 @@ from telemetry.page import page_test
 from telemetry.page.actions import action_runner
 from telemetry.timeline.model import TimelineModel
 from telemetry.util import statistics
+from telemetry.value import improvement_direction
 from telemetry.value import list_of_scalar_values
 from telemetry.value import scalar
 from telemetry.value import trace
@@ -65,23 +66,29 @@ def _AddTracingResults(events, results):
   for name in _NAMES_TO_DUMP:
     if values[name]:
       results.AddValue(list_of_scalar_values.ListOfScalarValues(
-          page, name, unit, values[name]))
+          page, name, unit, values[name],
+          improvement_direction=improvement_direction.DOWN))
       results.AddValue(scalar.ScalarValue(
-          page, name + '_max', unit, max(values[name])))
+          page, name + '_max', unit, max(values[name]),
+          improvement_direction=improvement_direction.DOWN))
     results.AddValue(scalar.ScalarValue(
-        page, name + '_total', unit, sum(values[name])))
+        page, name + '_total', unit, sum(values[name]),
+        improvement_direction=improvement_direction.DOWN))
 
   for do_type in ['mark', 'sweep']:
     work_time = 0
     for gc_type in ['precise', 'conservative']:
       work_time += sum(values['oilpan_%s_%s' % (gc_type, do_type)])
     key = 'oilpan_%s' % do_type
-    results.AddValue(scalar.ScalarValue(page, key, unit, work_time))
+    results.AddValue(scalar.ScalarValue(page, key, unit, work_time,
+                     improvement_direction=improvement_direction.DOWN))
 
   gc_time = 0
   for key in values:
     gc_time += sum(values[key])
-  results.AddValue(scalar.ScalarValue(page, 'oilpan_gc', unit, gc_time))
+  results.AddValue(scalar.ScalarValue(
+      page, 'oilpan_gc', unit, gc_time,
+      improvement_direction=improvement_direction.DOWN))
 
 
 class _OilpanGCTimesBase(page_test.PageTest):