[telemetry] Update examples so they work.

tools/telemetry/telemetry/core/extension_unittest.py

 # Copyright (c) 2012 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 logging
 import os
 import shutil
 import tempfile
 import unittest
 
@@ skipping 59 matching lines @@
                           extension_path, options.browser_type))
 
   def testExtensionNotLoaded(self):
     """Querying an extension that was not loaded will return None"""
     extension_path = os.path.join(util.GetUnittestDataDir(), 'simple_extension')
     options = options_for_unittests.GetCopy()
     load_extension = extension_to_load.ExtensionToLoad(
         extension_path, options.browser_type)
     browser_to_create = browser_finder.FindBrowser(options)
     with browser_to_create.Create() as b:
-      b.Start()
       if b.supports_extensions:
         self.assertRaises(extension_dict_backend.ExtensionNotFoundException,
                           lambda: b.extensions[load_extension])
 
 class MultipleExtensionTest(unittest.TestCase):
   def setUp(self):
     """ Copy the manifest and background.js files of simple_extension to a
     number of temporary directories to load as extensions"""
     self._extension_dirs = [tempfile.mkdtemp()
                             for i in range(3)] # pylint: disable=W0612
@@ skipping 51 matching lines @@
         extension_path, options.browser_type, is_component=True)
 
     options.extensions_to_load = [load_extension]
     browser_to_create = browser_finder.FindBrowser(options)
     if not browser_to_create:
       logging.warning('Did not find a browser that supports extensions, '
                       'skipping test.')
       return
 
     with browser_to_create.Create() as b:
-      b.Start()
       extension = b.extensions[load_extension]
       self.assertTrue(
           extension.EvaluateJavaScript('chrome.runtime != null'))
       extension.ExecuteJavaScript('setTestVar("abcdef")')
       self.assertEquals('abcdef', extension.EvaluateJavaScript('_testVar'))
 
   def testComponentExtensionNoPublicKey(self):
     # simple_extension does not have a public key.
     extension_path = os.path.join(util.GetUnittestDataDir(), 'simple_extension')
     options = options_for_unittests.GetCopy()
     self.assertRaises(extension_to_load.MissingPublicKeyException,
                       lambda: extension_to_load.ExtensionToLoad(
                           extension_path,
                           browser_type=options.browser_type,
                           is_component=True))