Obtain confidence score based off last known good and first known bad revision results.

tools/auto_bisect/bisect_results_test.py

Index: tools/auto_bisect/bisect_results_test.py
diff --git a/tools/auto_bisect/bisect_results_test.py b/tools/auto_bisect/bisect_results_test.py
index 25359c5e17c3d472178af0020ff931623896d7bf..b7d4cfa27f12cfef83f84bd9b7cb262a9a93bbdc 100644
--- a/tools/auto_bisect/bisect_results_test.py
+++ b/tools/auto_bisect/bisect_results_test.py
@@ -227,9 +227,9 @@ class BisectResultsTest(unittest.TestCase):
 
   def testWarningForTooLowConfidence(self):
     revision_states = self.mock_bisect_state.mock_revision_states
-    revision_states[2].value = {'values': [95, 100, 90]}
-    revision_states[3].value = {'values': [95, 100, 90]}
-    revision_states[4].value = {'values': [95, 100, 90]}
+    revision_states[2].value = {'values': [95, 90, 90]}

[RobertoCN, 2015/01/14 18:50:47]

Because of the new way of obtaining the confidence, needed to alter this test so
it would yield a confidence greater than 0, but yielding a warning.

[RobertoCN, 2015/01/30 21:23:32]

Done.

+    revision_states[3].value = {'values': [95, 90, 90]}
+    revision_states[4].value = {'values': [95, 90, 90]}
     results = BisectResults(self.mock_bisect_state, self.mock_depot_registry,
                             self.mock_opts, self.mock_warnings)
     self.assertGreater(results.confidence, 0)