Reduce flakiness of data reduction proxy integration tests.

Sometimes, the proxy information can be slow to come up on
chrome://net-internals#proxy, and this is the main cause of the current
flakiness in the chrome proxy integration tests. This change waits for
up to 10 seconds for the proxy information to come up.

BUG=427085

Review URL: https://codereview.chromium.org/707673002

Cr-Commit-Position: refs/heads/master@{#303066}

1 files changed, 10 insertions, 0 deletions

diff --git a/tools/chrome_proxy/integration_tests/chrome_proxy_metrics.py b/tools/chrome_proxy/integration_tests/chrome_proxy_metrics.py
index 3796f1a..890261e 100644
--- a/tools/chrome_proxy/integration_tests/chrome_proxy_metrics.py
+++ b/tools/chrome_proxy/integration_tests/chrome_proxy_metrics.py
@@ -7,6 +7,7 @@ import logging
 import os
 
 from integration_tests import network_metrics
+from telemetry.core import util
 from telemetry.page import page_test
 from telemetry.value import scalar
 
@@ -36,6 +37,15 @@ def GetProxyInfoFromNetworkInternals(tab, url='chrome://net-internals#proxy'):
     js = f.read()
     tab.ExecuteJavaScript(js)
   tab.WaitForJavaScriptExpression('performance.timing.loadEventStart', 300)
+
+  # Sometimes, the proxy information on net_internals#proxy is slow to come up.
+  # In order to prevent this from causing tests to flake frequently, wait for
+  # up to 10 seconds for this information to appear.
+  def IsDataReductionProxyEnabled():
+    info = tab.EvaluateJavaScript('window.__getChromeProxyInfo()')
+    return info['enabled']
+
+  util.WaitFor(IsDataReductionProxyEnabled, 10)
   info = tab.EvaluateJavaScript('window.__getChromeProxyInfo()')
   return info