[Sync] Convert DTCs to be not RefCounted and NonThreadSafe.

components/sync_sessions/session_data_type_controller.h

Index: components/sync_sessions/session_data_type_controller.h
diff --git a/components/sync_sessions/session_data_type_controller.h b/components/sync_sessions/session_data_type_controller.h
index beb0e11c15c124acc58013b5378b0fe9ed629ce1..06cebdfa339c15d2564cfbb00320aa081272ee45 100644
--- a/components/sync_sessions/session_data_type_controller.h
+++ b/components/sync_sessions/session_data_type_controller.h
@@ -19,12 +19,12 @@ namespace browser_sync {
 // device info to become available.
 class SessionDataTypeController : public sync_driver::UIDataTypeController {
  public:
-  SessionDataTypeController(
-      const scoped_refptr<base::SingleThreadTaskRunner>& ui_thread,
-      const base::Closure& error_callback,
-      sync_driver::SyncClient* sync_client,
-      sync_driver::LocalDeviceInfoProvider* local_device,
-      const char* history_disabled_pref_name);
+  // |dump_stack| is called when an unrecoverable error occurs.
+  SessionDataTypeController(const base::Closure& dump_stack,
+                            sync_driver::SyncClient* sync_client,
+                            sync_driver::LocalDeviceInfoProvider* local_device,
+                            const char* history_disabled_pref_name);
+  ~SessionDataTypeController() override;
 
   // UIDataTypeController interface.
   bool StartModels() override;
@@ -34,9 +34,6 @@ class SessionDataTypeController : public sync_driver::UIDataTypeController {
   // Called when asynchronous session restore has completed.
   void OnSessionRestoreComplete();
 
- protected:
-  ~SessionDataTypeController() override;
-
  private:
   bool IsWaiting();
   void MaybeCompleteLoading();