Refactor ExtensionTabUtil-namespaced functions into their own file.

chrome/chrome_browser.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.
 
 {
   'targets': [
     {
       'target_name': 'browser',
       'type': 'static_library',
       'dependencies': [
@@ skipping 1091 matching lines @@
         'browser/extensions/extension_sidebar_api.cc',
         'browser/extensions/extension_sidebar_api.h',
         'browser/extensions/extension_special_storage_policy.cc',
         'browser/extensions/extension_special_storage_policy.h',
         'browser/extensions/extension_sync_data.cc',
         'browser/extensions/extension_sync_data.h',
         'browser/extensions/extension_tab_helper.cc',
         'browser/extensions/extension_tab_helper.h',
         'browser/extensions/extension_tab_id_map.cc',
         'browser/extensions/extension_tab_id_map.h',
+        'browser/extensions/extension_tab_util.cc',
+        'browser/extensions/extension_tab_util.h',
         'browser/extensions/extension_tabs_module.cc',
         'browser/extensions/extension_tabs_module.h',
         'browser/extensions/extension_tabs_module_constants.cc',
         'browser/extensions/extension_tabs_module_constants.h',
         'browser/extensions/extension_test_api.cc',
         'browser/extensions/extension_test_api.h',
         'browser/extensions/extension_toolbar_model.cc',
         'browser/extensions/extension_toolbar_model.h',
         'browser/extensions/extension_tts_api.cc',
         'browser/extensions/extension_tts_api.h',
@@ skipping 3940 matching lines @@
               # weak imports in dependents, who still must #include
               # closure_blocks_leopard_compat.h to get weak imports.
               'type': 'none',
             }],
           ],
         },
       ],
     }],
   ],
 }