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

tools/perf/benchmarks/sunspider.py

Index: tools/perf/benchmarks/sunspider.py
diff --git a/tools/perf/benchmarks/sunspider.py b/tools/perf/benchmarks/sunspider.py
index 5db0cb612b1acded558f8cf838fbd57b9fe99f25..0bacea67d224c2f60794fbf79bfd55467a8cc032 100644
--- a/tools/perf/benchmarks/sunspider.py
+++ b/tools/perf/benchmarks/sunspider.py
@@ -10,6 +10,7 @@ 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
 
 
@@ -118,11 +119,13 @@ class _SunspiderMeasurement(page_test.PageTest):
     for key, values in r.iteritems():
       results.AddValue(list_of_scalar_values.ListOfScalarValues(
           results.current_page, key, 'ms', values, important=False,
-          description=DESCRIPTIONS.get(key)))
+          description=DESCRIPTIONS.get(key),
+          improvement_direction=improvement_direction.DOWN))
     results.AddValue(list_of_scalar_values.ListOfScalarValues(
         results.current_page, 'Total', 'ms', totals,
         description='Totals of run time for each different type of benchmark '
-                    'in sunspider'))
+                    'in sunspider',
+        improvement_direction=improvement_direction.DOWN))
 
 
 class Sunspider(benchmark.Benchmark):