Refactor BenchmarkResult.Add to take enum for data_type

tools/telemetry/telemetry/page/html_page_measurement_results.py

Index: tools/telemetry/telemetry/page/html_page_measurement_results.py
===================================================================
--- tools/telemetry/telemetry/page/html_page_measurement_results.py	(revision 218037)
+++ tools/telemetry/telemetry/page/html_page_measurement_results.py	(working copy)
@@ -10,6 +10,7 @@
 
 from telemetry.core import util
 from telemetry.page import buildbot_page_measurement_results
+from telemetry.page import result_data_type
 
 util.AddDirToPythonPath(util.GetChromiumSrcDir(), 'build', 'util')
 import lastchange  # pylint: disable=F0401
@@ -79,7 +80,7 @@
     self._output_stream.truncate()
 
   def _PrintPerfResult(self, measurement, trace, values, units,
-                       result_type='default'):
+                       result_type=result_data_type.DEFAULT):
     super(HtmlPageMeasurementResults, self)._PrintPerfResult(
         measurement, trace, values, units, result_type)
 
@@ -91,7 +92,7 @@
     self._result_json['tests'][self._test_name]['metrics'][metric_name] = {
         'current': values,
         'units': units,
-        'important': result_type == 'default'
+        'important': result_type == result_data_type.DEFAULT
         }
 
   def PrintSummary(self):