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

tools/perf/benchmarks/dromaeo.py

Index: tools/perf/benchmarks/dromaeo.py
diff --git a/tools/perf/benchmarks/dromaeo.py b/tools/perf/benchmarks/dromaeo.py
index 1f32d3923bdf36175d00c566a28d355b330d048b..b50fbcbc11805b9d4720f04812c5796c10b4634e 100644
--- a/tools/perf/benchmarks/dromaeo.py
+++ b/tools/perf/benchmarks/dromaeo.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 scalar
 
 
@@ -78,7 +79,8 @@ class _DromaeoMeasurement(page_test.PageTest):
       if name == suffix:
         important = True
       results.AddValue(scalar.ScalarValue(
-          results.current_page, Escape(name), 'runs/s', value, important))
+          results.current_page, Escape(name), 'runs/s', value, important,
+          improvement_direction=improvement_direction.UP))
 
     aggregated = {}
     for data in score: