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

tools/perf/benchmarks/speedometer.py

Index: tools/perf/benchmarks/speedometer.py
diff --git a/tools/perf/benchmarks/speedometer.py b/tools/perf/benchmarks/speedometer.py
index edcc2f1ec0fe2da357e9f477e7e92110466512ce..23fdca070e88c34c22fe1e4a703b54b5e737fae2 100644
--- a/tools/perf/benchmarks/speedometer.py
+++ b/tools/perf/benchmarks/speedometer.py
@@ -22,6 +22,7 @@ from telemetry import benchmark
 from telemetry import page as page_module
 from telemetry.page import page_set
 from telemetry.page import page_test
+from telemetry.value import improvement_direction
 from telemetry.value import list_of_scalar_values
 
 
@@ -62,7 +63,8 @@ class SpeedometerMeasurement(page_test.PageTest):
         'benchmarkClient._finishedTestCount == benchmarkClient.testsCount', 600)
     results.AddValue(list_of_scalar_values.ListOfScalarValues(
         page, 'Total', 'ms',
-        tab.EvaluateJavaScript('benchmarkClient._timeValues'), important=True))
+        tab.EvaluateJavaScript('benchmarkClient._timeValues'), important=True,
+        improvement_direction=improvement_direction.DOWN))
 
     # Extract the timings for each suite
     for suite_name in self.enabled_suites:
@@ -75,7 +77,8 @@ class SpeedometerMeasurement(page_test.PageTest):
                     benchmarkClient._measuredValues[i].tests['%s'].total);
               };
               suite_times;
-              """ % suite_name), important=False))
+              """ % suite_name), important=False,
+          improvement_direction=improvement_direction.DOWN))
 
 class Speedometer(benchmark.Benchmark):
   test = SpeedometerMeasurement