Fixing flaky integration test

tools/chrome_proxy/webdriver/bypass.py

 # Copyright 2017 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import common
 from common import TestDriver
 from common import IntegrationTest
 
 
 class Bypass(IntegrationTest):
@@ skipping 108 matching lines @@
       # proper via header. Chrome should bypass all proxies and retry the
       # request.
       test_driver.LoadURL(
           'http://chromeproxy-test.appspot.com/default?respStatus=414')
       responses = test_driver.GetHTTPResponses()
       self.assertNotEqual(0, len(responses))
       for response in responses:
         self.assertNotHasChromeProxyViaHeader(response)
         self.assertEqual(u'http/1.1', response.protocol)
 
-      # Check that the BlockTypePrimary histogram has a single entry in the
+      # Check that the BlockTypePrimary histogram has at least one entry in the
       # MissingViaHeader4xx category (which is enum value 4), to make sure that
       # the bypass was caused by the missing via header logic and not something
-      # else.
+      # else. The favicon for this URL may also be fetched, but will return a
+      # 404.
       histogram = test_driver.GetHistogram(
           "DataReductionProxy.BlockTypePrimary")
-      self.assertEqual(1, histogram['count'])
-      self.assertIn({'count': 1, 'high': 5, 'low': 4}, histogram['buckets'])
+      self.assertNotEqual(0, histogram['count'])
+      self.assertEqual(1, len(histogram['buckets']))
+      self.assertEqual(5, histogram['buckets'][0]['high'])
+      self.assertEqual(4, histogram['buckets'][0]['low'])
 
   # Verify that the Data Reduction Proxy understands the "exp" directive.
   def testExpDirectiveBypass(self):
     # If it was attempted to run with another experiment, skip this test.
     if common.ParseFlags().browser_args and ('--data-reduction-proxy-experiment'
         in common.ParseFlags().browser_args):
       self.skipTest('This test cannot be run with other experiments.')
     with TestDriver() as test_driver:
       test_driver.AddChromeArg('--enable-spdy-proxy-auth')
       test_driver.AddChromeArg('--data-reduction-proxy-experiment=test')
@@ skipping 37 matching lines @@
       test_driver.AddChromeArg('--data-reduction-proxy-http-proxies='
                                'http://compress.googlezip.net')  
           
       test_driver.LoadURL('http://check.googlezip.net/fallback/')
       responses = test_driver.GetHTTPResponses()      
       self.assertNotEqual(0, len(responses))
       for response in responses:        
         self.assertEqual(80, response.port)        
 
 if __name__ == '__main__':
-  IntegrationTest.RunAllTests()
+  IntegrationTest.RunAllTests()