Refactor BenchmarkResult.Add to take enum for data_type

tools/telemetry/telemetry/page/page_measurement_results_unittest.py

Index: tools/telemetry/telemetry/page/page_measurement_results_unittest.py
===================================================================
--- tools/telemetry/telemetry/page/page_measurement_results_unittest.py	(revision 222891)
+++ tools/telemetry/telemetry/page/page_measurement_results_unittest.py	(working copy)
@@ -4,10 +4,16 @@
 import os
 import unittest
 
+from telemetry.core import util
 from telemetry.page import page_measurement_results
 from telemetry.page import page_set
-from telemetry.page import perf_tests_helper
 
+# Get build scripts into our path.
+util.AddDirToPythonPath(util.GetChromiumSrcDir(), 'build', 'util', 'lib')
+from common import perf_result_data_type # pylint: disable=F0401
+from common import perf_tests_results_helper  # pylint: disable=F0401
+
+
 def _MakePageSet():
   return page_set.PageSet.FromDict({
       "description": "hello",
@@ -33,7 +39,8 @@
     self.results = []
 
   def _PrintPerfResult(self, *args):
-    res = perf_tests_helper.PrintPerfResult(*args, print_to_stdout=False)
+    res = perf_tests_results_helper.PrintPerfResult(*args,
+                                                    print_to_stdout=False)
     self.results.append(res)
 
 class PageMeasurementResultsTest(unittest.TestCase):
@@ -84,7 +91,9 @@
     measurement_results.WillMeasurePage(test_page_set.pages[1])
     self.assertRaises(
       AssertionError,
-      lambda: measurement_results.Add('a', 'seconds', 3, data_type='histogram'))
+      lambda: measurement_results.Add(
+          'a', 'seconds', 3,
+          data_type=perf_result_data_type.HISTOGRAM))
 
   def test_basic_summary_all_pages_fail(self):
     """If all pages fail, no summary is printed."""