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

tools/perf/benchmarks/octane.py

Index: tools/perf/benchmarks/octane.py
diff --git a/tools/perf/benchmarks/octane.py b/tools/perf/benchmarks/octane.py
index be50c621e513a72f86dcd484f8a65513c31b1042..831c2f7bc4bb779a2871513c58e1c06bf96a9695 100644
--- a/tools/perf/benchmarks/octane.py
+++ b/tools/perf/benchmarks/octane.py
@@ -117,7 +117,7 @@ class _OctaneMeasurement(page_test.PageTest):
         score = int(score_and_name[1])
         results.AddValue(scalar.ScalarValue(
             results.current_page, name, 'score', score, important=False,
-            description=DESCRIPTIONS.get(name)))
+            description=DESCRIPTIONS.get(name), higher_is_better=True))
 
         # Collect all test scores to compute geometric mean.
         all_scores.append(score)