sync: Move migration signal out of snapshot

sync/engine/sync_scheduler_impl.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/engine/sync_scheduler_impl.h"
 
 #include <algorithm>
 #include <cstring>
 
 #include "base/auto_reset.h"
@@ skipping 888 matching lines @@
                       OnActionableError(sync_protocol_error));
   }
 }
 
 void SyncSchedulerImpl::OnReceivedGuRetryDelay(const base::TimeDelta& delay) {
   nudge_tracker_.SetNextRetryTime(TimeTicks::Now() + delay);
   retry_timer_.Start(FROM_HERE, delay, this,
                      &SyncSchedulerImpl::RetryTimerCallback);
 }
 
+void SyncSchedulerImpl::OnReceivedMigrationRequest(ModelTypeSet types) {
+    FOR_EACH_OBSERVER(SyncEngineEventListener,
+                      *session_context_->listeners(),
+                      OnMigrationRequested(types));
+}
+
 void SyncSchedulerImpl::SetNotificationsEnabled(bool notifications_enabled) {
   DCHECK(CalledOnValidThread());
   session_context_->set_notifications_enabled(notifications_enabled);
   if (notifications_enabled)
     nudge_tracker_.OnInvalidationsEnabled();
   else
     nudge_tracker_.OnInvalidationsDisabled();
 }
 
 base::TimeDelta SyncSchedulerImpl::GetSessionsCommitDelay() const {
   DCHECK(CalledOnValidThread());
   return sessions_commit_delay_;
 }
 
 #undef SDVLOG_LOC
 
 #undef SDVLOG
 
 #undef SLOG
 
 #undef ENUM_CASE
 
 }  // namespace syncer