Cleanup of page_measurement_results object

tools/telemetry/telemetry/page/page_test_results.py

Index: tools/telemetry/telemetry/page/page_test_results.py
diff --git a/tools/telemetry/telemetry/page/page_test_results.py b/tools/telemetry/telemetry/page/page_test_results.py
index 20d314b6d64a78f7531378787e46ef9139c74d18..8c763fc7125aa0e68a059d548be446503c807072 100644
--- a/tools/telemetry/telemetry/page/page_test_results.py
+++ b/tools/telemetry/telemetry/page/page_test_results.py
@@ -10,9 +10,16 @@ import unittest
 class PageTestResults(unittest.TestResult):
   def __init__(self):
     super(PageTestResults, self).__init__()
+    self.pages_that_had_errors = set()
+    self.pages_that_had_failures = set()
     self.successes = []
     self.skipped = []
 
+  @property
+  def pages_that_had_errors_or_failures(self):
+    return self.pages_that_had_errors.union(
+      self.pages_that_had_failures)
+
   def _exc_info_to_string(self, err, test):
     if isinstance(test, unittest.TestCase):
       return super(PageTestResults, self)._exc_info_to_string(err, test)
@@ -32,9 +39,11 @@ class PageTestResults(unittest.TestResult):
     self.stopTest(page.display_name)
 
   def AddError(self, page, err):
+    self.pages_that_had_errors.add(page)
     self.addError(page.display_name, err)
 
   def AddFailure(self, page, err):
+    self.pages_that_had_failures.add(page)
     self.addFailure(page.display_name, err)
 
   def AddSuccess(self, page):