Refactor decorators into thier own python class

tools/chrome_proxy/webdriver/safebrowsing.py

 # Copyright 2017 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 common
 from common import TestDriver
 from common import IntegrationTest
-from common import AndroidOnly
-from common import NotAndroid
+from decorators import AndroidOnly
+from decorators import NotAndroid
 
 
 class SafeBrowsing(IntegrationTest):
 
   @AndroidOnly
   def testSafeBrowsingOn(self):
     with TestDriver() as t:
       t.AddChromeArg('--enable-spdy-proxy-auth')
       t.LoadURL('http://testsafebrowsing.appspot.com/s/malware.html')
       responses = t.GetHTTPResponses()
       self.assertEqual(0, len(responses))
 
   @NotAndroid
   def testSafeBrowsingOff(self):
     with TestDriver() as t:
       t.AddChromeArg('--enable-spdy-proxy-auth')
       t.LoadURL('http://testsafebrowsing.appspot.com/s/malware.html')
       responses = t.GetHTTPResponses()
       self.assertEqual(1, len(responses))
       for response in responses:
         self.assertHasChromeProxyViaHeader(response)
 
 if __name__ == '__main__':
   IntegrationTest.RunAllTests()