sync: Move migration signal out of snapshot

sync/internal_api/js_sync_manager_observer.cc

 // 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.
 
 #include "sync/internal_api/js_sync_manager_observer.h"
 
 #include <cstddef>
 
 #include "base/location.h"
 #include "base/logging.h"
@@ skipping 42 matching lines @@
     const SyncProtocolError& sync_error) {
   if (!event_handler_.IsInitialized()) {
     return;
   }
   base::DictionaryValue details;
   details.Set("syncError",  sync_error.ToValue());
   HandleJsEvent(FROM_HERE, "onActionableError",
                 JsEventDetails(&details));
 }
 
+void JsSyncManagerObserver::OnMigrationRequested(ModelTypeSet types) { }
+
 void JsSyncManagerObserver::OnInitializationComplete(
     const WeakHandle<JsBackend>& js_backend,
     const WeakHandle<DataTypeDebugInfoListener>& debug_info_listener,
     bool success, syncer::ModelTypeSet restored_types) {
   if (!event_handler_.IsInitialized()) {
     return;
   }
   // Ignore the |js_backend| argument; it's not really convertible to
   // JSON anyway.
 
@@ skipping 17 matching lines @@
     const std::string& name, const JsEventDetails& details) {
   if (!event_handler_.IsInitialized()) {
     NOTREACHED();
     return;
   }
   event_handler_.Call(from_here,
                       &JsEventHandler::HandleJsEvent, name, details);
 }
 
 }  // namespace syncer