Added integration test to Chrome Proxy to verify direct connection on remote site timeout

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 7c05b9517ef276252dfb6421111ff10ac04a47e0..a339d8f6c6a72ab6a5bd5d9269120a6f5a19ed70 100644
--- a/tools/chrome_proxy/integration_tests/chrome_proxy_measurements.py
+++ b/tools/chrome_proxy/integration_tests/chrome_proxy_measurements.py
@@ -13,6 +13,27 @@ from metrics import loading
 from telemetry.core import exceptions, util
 from telemetry.page import page_test
 

[sclittle, 2016/08/03 22:30:09]

Could you explain what the blackhole server does? Does it blackhole the initial
connection, or does it just blackhole after it receives the HTTP request headers
from the client?

+BLACKHOLE_SERVER_URL = 'http://blackhole-1470152441488.appspot.com'

[sclittle, 2016/08/03 22:30:09]

Where is the implementation of this? For simplicity, it might be better to
implement the server support as part of the chromeproxy testserver if possible:
https://cs.chromium.org/chromium/src/tools/chrome_proxy/testserver/ and the
external target is http://chromeproxy-test.appspot.com/

That way, the server implementation will be present in the open source codebase
here so that it can be modified easily by other people. Plus, it means that we
don't have to rely on an entirely different service to be up for the tests to
pass (meaning less flakiness), or worry about provisioning separately for this
service.

+
+class ChromeProxyClientBypassOnTimeout(ChromeProxyValidation):
+  """Tests that client bypasses proxy after proxy timeouts on HTTP

[sclittle, 2016/08/03 22:30:09]

nit: per Google Python style guide, the summary of the class comment or function
comment should all fit on one line.
https://google.github.io/styleguide/pyguide.html#Comments

[Robert Ogden, 2016/08/08 16:46:41]

Done.

+  response.
+  """
+
+  def __init__(self):
+    super(ChromeProxyClientBypassOnTimeout, self).__init__(
+        restart_after_each_page=True,
+        metrics=metrics.ChromeProxyMetric())
+
+  def CustomizeBrowserOptions(self, options):
+    super(ChromeProxyClientBypassOnTimeout, self).CustomizeBrowserOptions(
+        options)
+    self._is_chrome_proxy_enabled = False
+    options.AppendExtraBrowserArgs('--data-reduction-proxy-http-proxies='
+        + BLACKHOLE_SERVER_URL)
+
+  def AddResults(self, tab, results):
+    self._metrics.AddResultsForClientBypassOnTimeout(tab, results)
 
 class ChromeProxyDataSaving(page_test.PageTest):
   """Chrome proxy data saving measurement."""
@@ -677,4 +698,4 @@ class ChromeProxyPingback(ChromeProxyValidation):
       '--enable-stats-collection-bindings')
 
   def AddResults(self, tab, results):
-    self._metrics.AddResultsForPingback(tab, results)
+    self._metrics.AddResultsForPingback(tab, results)

[sclittle, 2016/08/03 22:30:09]

tiny nit: do you know what's up with the newline added here at the end? I don't
think it's really a problem, but could you remove it if you added it
accidentally?

[Robert Ogden, 2016/08/08 16:46:41]

bustamante@ and I both checked this out, there's not a newline at the end here
when you view the file. Not sure what's up with the diff