Add GetURL() and WaitForJSExpression() functions

tools/chrome_proxy/webdriver/simple_smoke.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 sys
 import time
 import unittest
 
 import common
 from common import TestDriver
 
 
 class SimpleSmoke(unittest.TestCase):
 
   # Simple example integration test.
   def testCheckPageWithProxy(self):
     with TestDriver() as t:
       t.AddChromeArg('--enable-spdy-proxy-auth')
-      t.SetURL('http://check.googlezip.net/test.html')
-      t.LoadPage()
+      t.LoadURL('http://check.googlezip.net/test.html')
       print 'Document Title: ', t.ExecuteJavascriptStatement('document.title',
         timeout=1)
-      time.sleep(5)
       responses = t.GetHTTPResponses()
       for response in responses:
         print "URL: %s, ViaHeader: %s, XHR: %s" % (response.url,
           response.ResponseHasViaHeader(), response.WasXHR())
 
   # Show how to get a histogram.
   def testPingbackHistogram(self):
     with TestDriver() as t:
       t.AddChromeArg('--enable-spdy-proxy-auth')
-      t.SetURL('http://check.googlezip.net/test.html')
-      t.LoadPage()
-      t.LoadPage()
+      t.LoadURL('http://check.googlezip.net/test.html')
+      t.LoadURL('http://check.googlezip.net/test.html')
       print t.GetHistogram('DataReductionProxy.Pingback.Attempted')
 
+  # Show how to use WaitForJavascriptExpression
+  def testHTML5(self):
+    with TestDriver() as t:
+      t.AddChromeArg('--enable-spdy-proxy-auth')
+      t.LoadURL('http://html5test.com/')
+      t.WaitForJavascriptExpression(
+        'document.getElementsByClassName("pointsPanel")', 15)
+
 if __name__ == '__main__':
   # The unittest library uses sys.argv itself and is easily confused by our
   # command line options. Pass it a simpler argv instead.
   unittest.main(argv=[sys.argv[0]], verbosity=2)