Add FailureValue and wire it through PageTestResults.

tools/telemetry/telemetry/results/page_test_results_unittest.py

Index: tools/telemetry/telemetry/results/page_test_results_unittest.py
diff --git a/tools/telemetry/telemetry/results/page_test_results_unittest.py b/tools/telemetry/telemetry/results/page_test_results_unittest.py
index 42dde5965e731468cf8f32fa098a73af0dca8a61..ba5690bd8f6ff6aa3b0464d1b70314f65e2b46cd 100644
--- a/tools/telemetry/telemetry/results/page_test_results_unittest.py
+++ b/tools/telemetry/telemetry/results/page_test_results_unittest.py
@@ -6,6 +6,7 @@ from telemetry.results import base_test_results_unittest
 
 from telemetry.page import page_set
 from telemetry.results import page_test_results
+from telemetry.value import failure
 
 class NonPrintingPageTestResults(
     page_test_results.PageTestResults):
@@ -28,8 +29,8 @@ class PageTestResultsTest(base_test_results_unittest.BaseTestResultsUnittest):
 
   def test_failures(self):
     results = NonPrintingPageTestResults()
-    results.AddFailure(self.pages[0], self.CreateException())
+    results.AddValue(
+        failure.FailureValue(self.pages[0], self.CreateException()))
     results.AddSuccess(self.pages[1])
-    self.assertEquals(results.pages_that_had_failures,
-                      set([self.pages[0]]))
+    self.assertEquals(results.pages_that_had_failures, [self.pages[0]])
     self.assertEquals(results.successes, [self.pages[1]])