[Sync] Move some code into new class JsMutationEventObserver

chrome/chrome.gyp

 # 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.
 {
   'variables': {
     'chromium_code': 1,
 
     'variables': {
       'version_py_path': 'tools/build/version.py',
       'version_path': 'VERSION',
@@ skipping 624 matching lines @@
         'browser/sync/engine/verify_updates_command.cc',
         'browser/sync/engine/verify_updates_command.h',
         'browser/sync/js/js_arg_list.cc',
         'browser/sync/js/js_arg_list.h',
         'browser/sync/js/js_backend.h',
         'browser/sync/js/js_controller.h',
         'browser/sync/js/js_event_details.cc',
         'browser/sync/js/js_event_details.h',
         'browser/sync/js/js_event_handler.h',
         'browser/sync/js/js_reply_handler.h',
+        'browser/sync/js/js_mutation_event_observer.cc',
+        'browser/sync/js/js_mutation_event_observer.h',
         'browser/sync/js/js_sync_manager_observer.cc',
         'browser/sync/js/js_sync_manager_observer.h',
-        'browser/sync/js/js_transaction_observer.cc',
-        'browser/sync/js/js_transaction_observer.h',
         'browser/sync/protocol/proto_enum_conversions.cc',
         'browser/sync/protocol/proto_enum_conversions.h',
         'browser/sync/protocol/proto_value_conversions.cc',
         'browser/sync/protocol/proto_value_conversions.h',
         'browser/sync/protocol/service_constants.h',
         'browser/sync/protocol/sync_protocol_error.cc',
         'browser/sync/protocol/sync_protocol_error.h',
         'browser/sync/sessions/ordered_commit_set.cc',
         'browser/sync/sessions/ordered_commit_set.h',
         'browser/sync/sessions/session_state.cc',
@@ skipping 1046 matching lines @@
             'destination': '<(PRODUCT_DIR)',
             'files': [
               '<(INTERMEDIATE_DIR)/repack/chrome.pak'
             ],
           },
         ],
       }],  # targets
     }],  # OS != "mac"
   ],  # 'conditions'
 }