Implement the Lo-Fi cache related integration tests with ChromeDriver

tools/chrome_proxy/webdriver/common.py

 # Copyright 2016 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 argparse
 import json
 import logging
 import os
 import re
 import socket
@@ skipping 530 matching lines @@
 
     Args:
       http_response: The HTTPResponse object to check.
     """
     expected_via_header = ParseFlags().via_header_value
     self.assertNotIn('via', http_response.response_headers)
     if 'via' in http_response.response_headers:
       self.assertNotIn(expected_via_header,
         http_response.response_headers['via'])
 
+  def assertLoFiResponse(self, http_response, expected_lo_fi):
+    """Asserts that the response and request headers contain the given directive
+    and the content size is less than 100 if |expected_lo_fi|. Otherwise, checks
+    that the response and request headers don't contain the Lo-Fi directive and
+    the content size is greater than 100.
+
+    Args:
+      http_response: The HTTPResponse object to check.
+      expected_lo_fi: Whether the response should be Lo-Fi.
+
+    Returns:
+      Whether the response was Lo-Fi.
+    """
+
+    if (expected_lo_fi) :
+      self.assertHasChromeProxyViaHeader(http_response)
+      content_length = http_response.response_headers['content-length']
+      cpat_request = http_response.request_headers[
+                       'chrome-proxy-accept-transform']
+      cpct_response = http_response.response_headers[
+                        'chrome-proxy-content-transform']
+      if ('empty-image' in cpct_response):
+        self.assertIn('empty-image', cpat_request)
+        self.assertTrue(int(content_length) < 100)
+        return True;
+      return False;
+    else:
+      self.assertNotIn('chrome-proxy-accept-transform',
+        http_response.request_headers)
+      self.assertNotIn('chrome-proxy-content-transform',
+        http_response.response_headers)
+      content_length = http_response.response_headers['content-length']
+      self.assertTrue(int(content_length) > 100)
+      return False;
+
   @staticmethod
   def RunAllTests(run_all_tests=False):
     """A simple helper method to run all tests using unittest.main().
 
     Args:
       run_all_tests: If True, all tests in the directory will be run, Otherwise
         only the tests in the file given on the command line will be run.
     """
     flags = ParseFlags()
     logger = GetLogger()
@@ skipping 81 matching lines @@
       args[0].skipTest('This test runs on Mac OS only.')
   return wrapper
 
 def NotMac(func):
   def wrapper(*args, **kwargs):
     if sys.platform == 'darwin':
       func(*args, **kwargs)
     else:
       args[0].skipTest('This test does not run on Mac OS.')
   return wrapper