Log the sync communication that happens between client and server.

chrome/chrome.gyp

 # 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.
 {
   'variables': {
     'chromium_code': 1,
 
     'variables': {
       'version_py_path': 'tools/build/version.py',
       'version_path': 'VERSION',
@@ skipping 395 matching lines @@
         'browser/sync/engine/syncer_command.h',
         'browser/sync/engine/syncer_proto_util.cc',
         'browser/sync/engine/syncer_proto_util.h',
         'browser/sync/engine/sync_scheduler.cc',
         'browser/sync/engine/sync_scheduler.h',
         'browser/sync/engine/syncer_types.cc',
         'browser/sync/engine/syncer_types.h',
         'browser/sync/engine/syncer_util.cc',
         'browser/sync/engine/syncer_util.h',
         'browser/sync/engine/syncproto.h',
+        'browser/sync/engine/traffic_logger.cc',
+        'browser/sync/engine/traffic_logger.h',
         'browser/sync/engine/update_applicator.cc',
         'browser/sync/engine/update_applicator.h',
         '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',
@@ skipping 927 matching lines @@
           'sources': [
             'browser/safe_browsing/signature_util.h',
             'browser/safe_browsing/signature_util_win.cc',
             'tools/safe_browsing/sb_sigutil.cc',
           ],
         },
       ]},  # 'targets'
     ],  # OS=="win"
   ],  # 'conditions'
 }