Wire sync shutdown reason from PSS all the way down to sync manager.

sync/sync.gyp

 # Copyright 2013 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,
   },
 
   'includes': [
@@ skipping 244 matching lines @@
         'internal_api/public/http_bridge_network_resources.h',
         'internal_api/public/http_post_provider_factory.h',
         'internal_api/public/http_post_provider_interface.h',
         'internal_api/public/internal_components_factory.h',
         'internal_api/public/internal_components_factory_impl.h',
         'internal_api/public/network_resources.h',
         'internal_api/public/non_blocking_sync_common.cc',
         'internal_api/public/non_blocking_sync_common.h',
         'internal_api/public/read_node.h',
         'internal_api/public/read_transaction.h',
+        'internal_api/public/shutdown_reason.h',
         'internal_api/public/sessions/commit_counters.cc',
         'internal_api/public/sessions/commit_counters.h',
         'internal_api/public/sessions/model_neutral_state.cc',
         'internal_api/public/sessions/model_neutral_state.h',
         'internal_api/public/sessions/status_counters.cc',
         'internal_api/public/sessions/status_counters.h',
         'internal_api/public/sessions/sync_session_snapshot.cc',
         'internal_api/public/sessions/sync_session_snapshot.h',
         'internal_api/public/sessions/type_debug_info_observer.cc',
         'internal_api/public/sessions/type_debug_info_observer.h',
@@ skipping 230 matching lines @@
         'proto_out_dir': 'sync/protocol',
         'cc_generator_options': 'dllexport_decl=SYNC_PROTO_EXPORT:',
         'cc_include': 'sync/protocol/sync_proto_export.h',
       },
       'includes': [
         '../build/protoc.gypi'
       ],
     },
   ],
 }