[Sync] Convert SyncSessions to NonUIDataTypeController and remove UIDataTypeController

components/sync_sessions/sessions_sync_manager.cc

Index: components/sync_sessions/sessions_sync_manager.cc
diff --git a/components/sync_sessions/sessions_sync_manager.cc b/components/sync_sessions/sessions_sync_manager.cc
index acb6882b7bcae3f68e4bfc4110af0daf1694b060..04e01b70a32a5d0de015a3d9c00bc21bd9a2f004 100644
--- a/components/sync_sessions/sessions_sync_manager.cc
+++ b/components/sync_sessions/sessions_sync_manager.cc
@@ -92,6 +92,7 @@ SessionsSyncManager::SessionsSyncManager(
       local_tab_pool_out_of_sync_(true),
       sync_prefs_(sync_prefs),
       local_device_(local_device),
+      current_device_type_(sync_pb::SyncEnums_DeviceType_TYPE_OTHER),
       local_session_header_node_id_(TabNodePool::kInvalidTabNodeID),
       stale_session_threshold_days_(kDefaultStaleSessionThresholdDays),
       local_event_router_(std::move(router)),
@@ -121,6 +122,19 @@ syncer::SyncMergeResult SessionsSyncManager::MergeDataAndStartSyncing(
   error_handler_ = std::move(error_handler);
   sync_processor_ = std::move(sync_processor);
 
+  // SessionDataTypeController ensures that the local device info
+  // is available before activating this datatype.
+  DCHECK(local_device_);
+  const DeviceInfo* local_device_info = local_device_->GetLocalDeviceInfo();
+  if (!local_device_info) {
+    merge_result.set_error(error_handler_->CreateAndUploadError(
+        FROM_HERE, "Failed to get local device info."));
+    return merge_result;
+  }
+
+  current_session_name_ = local_device_info->client_name();
+  current_device_type_ = local_device_info->device_type();
+
   // It's possible(via RebuildAssociations) for lost_navigations_recorder_ to
   // persist between sync being stopped and started. If it did persist, it's
   // already associated with |sync_processor|, so leave it alone.
@@ -136,19 +150,7 @@ syncer::SyncMergeResult SessionsSyncManager::MergeDataAndStartSyncing(
   // a conveniently safe time to assert sync is ready and the cache_guid is
   // initialized.
   if (current_machine_tag_.empty()) {
-    InitializeCurrentMachineTag();
-  }
-
-  // SessionDataTypeController ensures that the local device info
-  // is available before activating this datatype.
-  DCHECK(local_device_);
-  const DeviceInfo* local_device_info = local_device_->GetLocalDeviceInfo();
-  if (local_device_info) {
-    current_session_name_ = local_device_info->client_name();
-  } else {
-    merge_result.set_error(error_handler_->CreateAndUploadError(
-        FROM_HERE, "Failed to get local device info."));
-    return merge_result;
+    InitializeCurrentMachineTag(local_device_->GetLocalSyncCacheGUID());
   }
 
   session_tracker_.SetLocalSessionTag(current_machine_tag_);
@@ -164,7 +166,7 @@ syncer::SyncMergeResult SessionsSyncManager::MergeDataAndStartSyncing(
     base_specifics->set_session_tag(current_machine_tag());
     sync_pb::SessionHeader* header_s = base_specifics->mutable_header();
     header_s->set_client_name(current_session_name_);
-    header_s->set_device_type(local_device_info->device_type());
+    header_s->set_device_type(current_device_type_);
     syncer::SyncData data = syncer::SyncData::CreateLocalData(
         current_machine_tag(), current_session_name_, specifics);
     new_changes.push_back(
@@ -200,11 +202,7 @@ void SessionsSyncManager::AssociateWindows(
   SyncedSession* current_session = session_tracker_.GetSession(local_tag);
   current_session->modified_time = base::Time::Now();
   header_s->set_client_name(current_session_name_);
-  // SessionDataTypeController ensures that the local device info
-  // is available before activating this datatype.
-  DCHECK(local_device_);
-  const DeviceInfo* local_device_info = local_device_->GetLocalDeviceInfo();
-  header_s->set_device_type(local_device_info->device_type());
+  header_s->set_device_type(current_device_type_);
 
   session_tracker_.ResetSessionTracking(local_tag);
   std::set<const SyncedWindowDelegate*> windows =
@@ -389,7 +387,7 @@ void SessionsSyncManager::AssociateTab(SyncedTabDelegate* const tab,
       base::Time::Now();
 }
 
-void SessionsSyncManager::RebuildAssociations() {
+bool SessionsSyncManager::RebuildAssociations() {
   syncer::SyncDataList data(sync_processor_->GetAllSyncData(syncer::SESSIONS));
   std::unique_ptr<syncer::SyncErrorFactory> error_handler(
       std::move(error_handler_));
@@ -397,8 +395,9 @@ void SessionsSyncManager::RebuildAssociations() {
       std::move(sync_processor_));
 
   StopSyncing(syncer::SESSIONS);
-  MergeDataAndStartSyncing(syncer::SESSIONS, data, std::move(processor),
-                           std::move(error_handler));
+  syncer::SyncMergeResult merge_result = MergeDataAndStartSyncing(
+      syncer::SESSIONS, data, std::move(processor), std::move(error_handler));
+  return !merge_result.error().IsSet();
 }
 
 bool SessionsSyncManager::IsValidSessionHeader(
@@ -434,8 +433,8 @@ void SessionsSyncManager::OnLocalTabModified(SyncedTabDelegate* modified_tab) {
   if (local_tab_pool_out_of_sync_) {
     // If our tab pool is corrupt, pay the price of a full re-association to
     // fix things up.  This takes care of the new tab modification as well.
-    RebuildAssociations();
-    DCHECK(!local_tab_pool_out_of_sync_);
+    bool rebuild_association_succeeded = RebuildAssociations();
+    DCHECK(!rebuild_association_succeeded || !local_tab_pool_out_of_sync_);
     return;
   }
 
@@ -767,7 +766,8 @@ void SessionsSyncManager::UpdateTrackerWithForeignSession(
   }
 }
 
-void SessionsSyncManager::InitializeCurrentMachineTag() {
+void SessionsSyncManager::InitializeCurrentMachineTag(
+    const std::string& cache_guid) {
   DCHECK(current_machine_tag_.empty());
   std::string persisted_guid;
   persisted_guid = sync_prefs_->GetSyncSessionsGUID();
@@ -775,8 +775,6 @@ void SessionsSyncManager::InitializeCurrentMachineTag() {
     current_machine_tag_ = persisted_guid;
     DVLOG(1) << "Restoring persisted session sync guid: " << persisted_guid;
   } else {
-    DCHECK(local_device_);
-    std::string cache_guid = local_device_->GetLocalSyncCacheGUID();
     DCHECK(!cache_guid.empty());
     current_machine_tag_ = BuildMachineTag(cache_guid);
     DVLOG(1) << "Creating session sync guid: " << current_machine_tag_;