Allow chromedriver to install an extension and get all installed extension IDs.

chrome/chrome_tests.gypi

 # Copyright (c) 2011 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.
 {
   'target_defaults': {
     'conditions': [
       ['strip_tests==1', {
         'cflags!': [ '-g' ],
         'ldflags': [ '-Wl,--strip-debug' ],
       }],
@@ skipping 942 matching lines @@
       'include_dirs': [
         '..',
       ],
       'sources': [
         'test/webdriver/commands/alert_commands.cc',
         'test/webdriver/commands/alert_commands.h',
         'test/webdriver/commands/appcache_status_command.cc',
         'test/webdriver/commands/appcache_status_command.h',
         'test/webdriver/commands/browser_connection_commands.cc',
         'test/webdriver/commands/browser_connection_commands.h',
+        'test/webdriver/commands/chrome_commands.cc',
+        'test/webdriver/commands/chrome_commands.h',
         'test/webdriver/commands/command.cc',
         'test/webdriver/commands/command.h',
         'test/webdriver/commands/cookie_commands.cc',
         'test/webdriver/commands/cookie_commands.h',
         'test/webdriver/commands/create_session.cc',
         'test/webdriver/commands/create_session.h',
         'test/webdriver/commands/execute_async_script_command.cc',
         'test/webdriver/commands/execute_async_script_command.h',
         'test/webdriver/commands/execute_command.cc',
         'test/webdriver/commands/execute_command.h',
@@ skipping 3369 matching lines @@
               # Use outputs of this action as inputs for the main target build.
               # Seems as a misnomer but makes this happy on Linux (scons).
               'process_outputs_as_sources': 1,
             },
           ],  # 'actions'
         },
       ]
     }],  # 'coverage!=0'
   ],  # 'conditions'
 }