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

tools/perf/benchmarks/service_worker.py

Index: tools/perf/benchmarks/service_worker.py
diff --git a/tools/perf/benchmarks/service_worker.py b/tools/perf/benchmarks/service_worker.py
index 9ab014a650a065a0e40d2b9204084c9b8eefef46..0f5ef126489c959bba77129bd60fb3dfba6501b2 100644
--- a/tools/perf/benchmarks/service_worker.py
+++ b/tools/perf/benchmarks/service_worker.py
@@ -29,10 +29,11 @@ class _ServiceWorkerTimelineMetric(object):
       sanitized_counter_name = counter_name.replace('.', '_')
 
       results.AddValue(scalar.ScalarValue(
-          results.current_page, sanitized_counter_name, 'count', total))
+          results.current_page, sanitized_counter_name, 'count', total,
+          higher_is_better=False))
       results.AddValue(scalar.ScalarValue(
           results.current_page, sanitized_counter_name + '_avg', 'count',
-          total / float(len(counter.totals))))
+          total / float(len(counter.totals)), higher_is_better=False))
 
   def AddResultsOfEvents(
       self, process, thread_regex_string, event_regex_string, results):
@@ -75,11 +76,13 @@ class _ServiceWorkerTimelineMetric(object):
 
     full_name = thread_name + '|' + sanitized_event_name
     results.AddValue(scalar.ScalarValue(
-        results.current_page, full_name, 'ms', total))
+        results.current_page, full_name, 'ms', total, higher_is_better=False))
     results.AddValue(scalar.ScalarValue(
-        results.current_page, full_name + '_max', 'ms', biggest_jank))
+        results.current_page, full_name + '_max', 'ms', biggest_jank,
+        higher_is_better=False))
     results.AddValue(scalar.ScalarValue(
-        results.current_page, full_name + '_avg', 'ms', total / len(times)))
+        results.current_page, full_name + '_avg', 'ms', total / len(times),
+        higher_is_better=False))
 
 
 class _ServiceWorkerMeasurement(page_test.PageTest):