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

tools/perf/measurements/skpicture_printer.py

Index: tools/perf/measurements/skpicture_printer.py
diff --git a/tools/perf/measurements/skpicture_printer.py b/tools/perf/measurements/skpicture_printer.py
index fd41e67ddc6844248327875f66078f1ddbe296da..f9c109dce02b695016d28f49941f04b0932fb924 100644
--- a/tools/perf/measurements/skpicture_printer.py
+++ b/tools/perf/measurements/skpicture_printer.py
@@ -5,6 +5,7 @@ import glob
 import os
 
 from telemetry.page import page_test
+from telemetry.value import improvement_direction
 from telemetry.value import scalar
 
 
@@ -33,4 +34,5 @@ class SkpicturePrinter(page_test.PageTest):
     tab.EvaluateJavaScript(js)
     pictures = glob.glob(os.path.join(outpath, '*.skp'))
     results.AddValue(scalar.ScalarValue(
-        results.current_page, 'saved_picture_count', 'count', len(pictures)))
+        results.current_page, 'saved_picture_count', 'count', len(pictures),
+        improvement_direction=improvement_direction.DOWN))