Refactor BenchmarkResult.Add to take enum for data_type

tools/perf/measurements/dromaeo.py

Index: tools/perf/measurements/dromaeo.py
===================================================================
--- tools/perf/measurements/dromaeo.py	(revision 222891)
+++ tools/perf/measurements/dromaeo.py	(working copy)
@@ -5,6 +5,10 @@
 from telemetry.core import util
 from telemetry.page import page_measurement
 
+# Get build scripts into our path.
+util.AddDirToPythonPath(util.GetChromiumSrcDir(), 'build', 'util', 'lib')
+from common import perf_result_data_type # pylint: disable=F0401
+
 class Dromaeo(page_measurement.PageMeasurement):
   def MeasurePage(self, page, tab, results):
     js_is_done = 'window.document.cookie.indexOf("__done=1") >= 0'
@@ -24,7 +28,7 @@
 
     suffix = page.url[page.url.index('?') + 1 : page.url.index('&')]
     for k, v in score.iteritems():
-      data_type = 'unimportant'
+      data_type = perf_result_data_type.UNIMPORTANT
       if k == suffix:
-        data_type = 'default'
+        data_type = perf_result_data_type.DEFAULT
       results.Add(Escape(k), 'runs/s', v, data_type=data_type)