sync: Move migration signal out of snapshot

chrome/browser/sync/glue/sync_backend_host_core.cc

 // 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.
 
 #include "chrome/browser/sync/glue/sync_backend_host_core.h"
 
 #include "base/command_line.h"
 #include "base/file_util.h"
 #include "base/metrics/histogram.h"
 #include "chrome/browser/sync/glue/device_info.h"
@@ skipping 299 matching lines @@
     const syncer::SyncProtocolError& sync_error) {
   if (!sync_loop_)
     return;
   DCHECK_EQ(base::MessageLoop::current(), sync_loop_);
   host_.Call(
       FROM_HERE,
       &SyncBackendHostImpl::HandleActionableErrorEventOnFrontendLoop,
       sync_error);
 }
 
+void SyncBackendHostCore::OnMigrationRequested(syncer::ModelTypeSet types) {
+  DCHECK_EQ(base::MessageLoop::current(), sync_loop_);
+  host_.Call(
+      FROM_HERE,
+      &SyncBackendHostImpl::HandleMigrationRequestedOnFrontendLoop,
+      types);
+}
+
 void SyncBackendHostCore::DoOnInvalidatorStateChange(
     syncer::InvalidatorState state) {
   DCHECK_EQ(base::MessageLoop::current(), sync_loop_);
   sync_manager_->OnInvalidatorStateChange(state);
 }
 
 void SyncBackendHostCore::DoOnIncomingInvalidation(
     const syncer::ObjectIdInvalidationMap& invalidation_map) {
   DCHECK_EQ(base::MessageLoop::current(), sync_loop_);
   sync_manager_->OnIncomingInvalidation(invalidation_map);
@@ skipping 283 matching lines @@
       this, &SyncBackendHostCore::SaveChanges);
 }
 
 void SyncBackendHostCore::SaveChanges() {
   DCHECK_EQ(base::MessageLoop::current(), sync_loop_);
   sync_manager_->SaveChanges();
 }
 
 }  // namespace browser_sync