Added integration test to Chrome Proxy to verify fallback to HTTP after bad HTTPS response from pro…

tools/chrome_proxy/integration_tests/chrome_proxy_measurements.py

Index: tools/chrome_proxy/integration_tests/chrome_proxy_measurements.py
diff --git a/tools/chrome_proxy/integration_tests/chrome_proxy_measurements.py b/tools/chrome_proxy/integration_tests/chrome_proxy_measurements.py
index 59903ddc8320b510f056ff3ef3964bd4ccb4a979..1c6fdaa4ff07492e00d16a5c02764cb034070af7 100644
--- a/tools/chrome_proxy/integration_tests/chrome_proxy_measurements.py
+++ b/tools/chrome_proxy/integration_tests/chrome_proxy_measurements.py
@@ -195,6 +195,21 @@ def GetResponseOverrideURL(url=_TEST_SERVER_DEFAULT_URL, respStatus=0,
   else:
     return url + '?' + "&".join(queries)
 
+class ChromeProxyBadHTTPSFallback(ChromeProxyValidation):
+  """Checks the client falls back to HTTP proxy when HTTPS proxy errors."""
+
+  def __init__(self):
+    super(ChromeProxyBadHTTPSFallback, self).__init__(
+        restart_after_each_page=True,
+        metrics=metrics.ChromeProxyMetric())
+    self._is_chrome_proxy_enabled = True
+
+  def CustomizeBrowserOptions(self, options):
+    super(ChromeProxyBadHTTPSFallback, self).CustomizeBrowserOptions(
+        options)
+
+  def AddResults(self, tab, results):
+    self._metrics.AddResultsForBadHTTPSFallback(tab, results)
 
 class ChromeProxyHTTPFallbackProbeURL(ChromeProxyValidation):
   """Correctness measurement for proxy fallback.