Refactor BenchmarkResult.Add to take enum for data_type

tools/perf/benchmarks/octane.py

Index: tools/perf/benchmarks/octane.py
===================================================================
--- tools/perf/benchmarks/octane.py	(revision 222891)
+++ tools/perf/benchmarks/octane.py	(working copy)
@@ -9,7 +9,11 @@
 from telemetry.page import page_measurement
 from telemetry.page import page_set
 
+# Get build scripts into our path.
+util.AddDirToPythonPath(util.GetChromiumSrcDir(), 'build', 'util', 'lib')
+from common import perf_result_data_type # pylint: disable=F0401
 
+
 class OctaneMeasurement(page_measurement.PageMeasurement):
   def MeasurePage(self, _, tab, results):
     js_is_done = """
@@ -36,9 +40,9 @@
     for key, value in result_dict.iteritems():
       if value == '...':
         continue
-      data_type = 'unimportant'
+      data_type = perf_result_data_type.UNIMPORTANT
       if key == 'score':
-        data_type = 'default'
+        data_type = perf_result_data_type.DEFAULT
       results.Add(key, 'score (bigger is better)', value, data_type=data_type)