Adds Lo-Fi fallback support for new Data Reduction Proxy protocol.

tools/chrome_proxy/webdriver/lite_page.py

Index: tools/chrome_proxy/webdriver/lite_page.py
diff --git a/tools/chrome_proxy/webdriver/lite_page.py b/tools/chrome_proxy/webdriver/lite_page.py
index 39b6d43e5b7722152b238d39b096899266a5d094..44b68a9f98fa89aac438ff4752a69e5dd2b0078f 100644
--- a/tools/chrome_proxy/webdriver/lite_page.py
+++ b/tools/chrome_proxy/webdriver/lite_page.py
@@ -99,7 +99,7 @@ class LitePage(IntegrationTest):
 
   # Lo-Fi fallback is not currently supported via the client. Check that

[megjablon, 2017/06/05 23:47:59]

Update this to "Lo-Fi fallback is not supported without the
DataReductionProxyDecidesTransform feature. Check that no Lo-Fi response is
received if a Lite Page is not served."

[dougarnett, 2017/06/06 16:49:47]

Done.

   # no Lo-Fi response is received if a Lite Page is not served.
-  def testLitePageFallback(self):
+  def testLitePageNoFallback(self):
     with TestDriver() as test_driver:
       test_driver.AddChromeArg('--enable-spdy-proxy-auth')
       test_driver.AddChromeArg('--force-fieldtrials='
@@ -134,5 +134,43 @@ class LitePage(IntegrationTest):
       # Verify that a Lite Page was requested.
       self.assertEqual(1, lite_page_requests)
 
+  # Verifies Lo-Fi fallback via the page-policies server directive.
+  # Note: this test is for the CPAT protocol change in M-61.
+  def testLitePageFallbackViaPagePolicies(self):

[megjablon, 2017/06/05 23:47:59]

Please also add tests with DataReductionProxyDecidesTransform feature on for
forcing a lite page via the flag and for forcing Lo-Fi enabled with the flag

[dougarnett, 2017/06/06 16:49:46]

In different CL? I don't see how these tests would apply to this change. I have
several more integration tests that I want to add (some already coded) - pending
server support pushing out to prod (also force_empty_image is not yet
implemented by the server but initial test for it verifying client sends force
exp is in another CL).

[dougarnett, 2017/06/07 16:57:49]

I went ahead and added my integration tests here for getting lite page for slow
connection but not for fast connection with new feature on. These work now
against staging but not yet for prod server (as ECT checking change has not yet
pushed to prod - should by end of week). 

+    with TestDriver() as test_driver:
+      test_driver.AddChromeArg('--enable-spdy-proxy-auth')
+      test_driver.AddChromeArg('--enable-features='
+                               'DataReductionProxyDecidesTransform')
+      test_driver.AddChromeArg('--force-fieldtrial-params='
+                               'NetworkQualityEstimator.Enabled:'
+                               'force_effective_connection_type/Slow2G,'
+                               'DataCompressionProxyLoFi.Enabled_Preview:'
+                               'effective_connection_type/2G')
+      test_driver.AddChromeArg('--force-fieldtrials='
+                               'NetworkQualityEstimator/Enabled/'
+                               'DataCompressionProxyLoFi/Enabled_Preview')
+
+      test_driver.LoadURL('http://check.googlezip.net/lite-page-fallback')
+
+      lite_page_responses = 0
+      lofi_resource = 0
+      for response in test_driver.GetHTTPResponses():
+        self.assertEqual('Slow-2G',
+                         response.request_headers['chrome-proxy-ect'])
+
+        if response.url.endswith('html'):
+          # Verify that the server provides the fallback directive
+          self.assertIn('page-policies=empty-image',
+                        response.response_headers['chrome-proxy'])
+          # Main resource should not accept and transform to lite page.
+          if self.checkLitePageResponse(response):
+            lite_page_responses = lite_page_responses + 1
+        if response.url.endswith('png'):
+          if self.checkLoFiResponse(response, True):
+            lofi_resource = lofi_resource + 1
+
+      self.assertEqual(0, lite_page_responses)
+      self.assertNotEqual(0, lofi_resource)
+
 if __name__ == '__main__':
   IntegrationTest.RunAllTests()