[Sync] ModelTypeStore factory shouldn't require valid PSS to function correctly

components/browser_sync/profile_sync_service.cc

Index: components/browser_sync/profile_sync_service.cc
diff --git a/components/browser_sync/profile_sync_service.cc b/components/browser_sync/profile_sync_service.cc
index 34924acfd233a60fea08d540a4569438d8379b58..9e63dfeb33a7c7b80180c7a2e40eb792d63a7bea 100644
--- a/components/browser_sync/profile_sync_service.cc
+++ b/components/browser_sync/profile_sync_service.cc
@@ -148,9 +148,6 @@ const net::BackoffEntry::Policy kRequestAccessTokenBackoffPolicy = {
     false,
 };
 
-const base::FilePath::CharType kLevelDBFolderName[] =
-    FILE_PATH_LITERAL("LevelDB");
-
 }  // namespace
 
 ProfileSyncService::InitParams::InitParams() = default;
@@ -171,7 +168,6 @@ ProfileSyncService::ProfileSyncService(InitParams init_params)
       network_time_update_callback_(
           std::move(init_params.network_time_update_callback)),
       url_request_context_(init_params.url_request_context),
-      blocking_task_runner_(std::move(init_params.blocking_task_runner)),
       is_first_time_sync_configure_(false),
       engine_initialized_(false),
       sync_disabled_by_admin_(false),
@@ -249,8 +245,11 @@ void ProfileSyncService::Initialize() {
     // TODO(skym): Stop creating leveldb files when signed out.
     // TODO(skym): Verify using AsUTF8Unsafe is okay here. Should work as long
     // as the Local State file is guaranteed to be UTF-8.
+    const syncer::ModelTypeStoreFactory& store_factory =
+        GetModelTypeStoreFactory(syncer::DEVICE_INFO, base_directory_,
+                                 sync_client_->GetBlockingPool());
     device_info_sync_bridge_ = base::MakeUnique<DeviceInfoSyncBridge>(
-        local_device_.get(), GetModelTypeStoreFactory(syncer::DEVICE_INFO),
+        local_device_.get(), store_factory,
         base::BindRepeating(
             &ModelTypeChangeProcessor::Create,
             base::BindRepeating(&syncer::ReportUnrecoverableError, channel_)));
@@ -558,7 +557,7 @@ void ProfileSyncService::StartUpSlowEngineComponents() {
 
   engine_.reset(sync_client_->GetSyncApiComponentFactory()->CreateSyncEngine(
       debug_identifier_, invalidator, sync_prefs_.AsWeakPtr(),
-      sync_data_folder_));
+      FormatSyncDataPath(base_directory_)));
 
   // Clear any old errors the first time sync starts.
   if (!IsFirstSetupComplete())
@@ -694,7 +693,7 @@ void ProfileSyncService::ShutdownImpl(syncer::ShutdownReason reason) {
       sync_thread_->task_runner()->PostTask(
           FROM_HERE,
           base::Bind(&syncer::syncable::Directory::DeleteDirectoryFiles,
-                     sync_data_folder_));
+                     FormatSyncDataPath(base_directory_)));
     }
     return;
   }
@@ -930,7 +929,7 @@ void ProfileSyncService::OnEngineInitialized(
 
   // Initialize local device info.
   local_device_->Initialize(cache_guid, signin_scoped_device_id,
-                            blocking_task_runner_);
+                            sync_client_->GetBlockingPool());
 
   if (protocol_event_observers_.might_have_observers()) {
     engine_->RequestBufferedProtocolEventsAndEnableForwarding();
@@ -1670,12 +1669,21 @@ void ProfileSyncService::SetPlatformSyncAllowedProvider(
   platform_sync_allowed_provider_ = platform_sync_allowed_provider;
 }
 
+// static
 syncer::ModelTypeStoreFactory ProfileSyncService::GetModelTypeStoreFactory(
-    ModelType type) {
-  return base::Bind(&ModelTypeStore::CreateStore, type,
-                    sync_data_folder_.Append(base::FilePath(kLevelDBFolderName))
-                        .AsUTF8Unsafe(),
-                    blocking_task_runner_);
+    ModelType type,
+    const base::FilePath& base_path,
+    base::SequencedWorkerPool* blocking_pool) {
+  // TODO(skym): Verify using AsUTF8Unsafe is okay here. Should work as long
+  // as the Local State file is guaranteed to be UTF-8.
+  std::string path = FormatSharedModelTypeStorePath(base_path).AsUTF8Unsafe();
+  base::SequencedWorkerPool::SequenceToken sequence_token =
+      blocking_pool->GetNamedSequenceToken(path);

[skym, 2017/03/08 19:28:15]

Cool!

+  scoped_refptr<base::SequencedTaskRunner> task_runner =
+      blocking_pool->GetSequencedTaskRunnerWithShutdownBehavior(
+          blocking_pool->GetNamedSequenceToken(path),
+          base::SequencedWorkerPool::SKIP_ON_SHUTDOWN);
+  return base::Bind(&ModelTypeStore::CreateStore, type, path, task_runner);
 }
 
 void ProfileSyncService::ConfigureDataTypeManager() {
@@ -2330,7 +2338,7 @@ void ProfileSyncService::FlushDirectory() const {
 
 base::FilePath ProfileSyncService::GetDirectoryPathForTest() const {
   DCHECK(thread_checker_.CalledOnValidThread());
-  return sync_data_folder_;
+  return FormatSyncDataPath(base_directory_);
 }
 
 base::MessageLoop* ProfileSyncService::GetSyncLoopForTest() const {