[Sync] Make SMTP always have the dump stack function.

components/sync/driver/data_type_controller.h

Index: components/sync/driver/data_type_controller.h
diff --git a/components/sync/driver/data_type_controller.h b/components/sync/driver/data_type_controller.h
index aef685cdbc2cb6afcf85026f484a8db39d22830a..812a190432920e70c434d59e43720a71456cd523 100644
--- a/components/sync/driver/data_type_controller.h
+++ b/components/sync/driver/data_type_controller.h
@@ -157,14 +157,11 @@ class DataTypeController : public base::SupportsWeakPtr<DataTypeController> {
   virtual void GetStatusCounters(const StatusCountersCallback& callback) = 0;
 
  protected:
-  DataTypeController(ModelType type, const base::Closure& dump_stack);
+  explicit DataTypeController(ModelType type);
 
   // Allows subclasses to DCHECK that they're on the correct thread.
   bool CalledOnValidThread() const;
 
-  // Callback to dump and upload a stack trace when an error occurs.
-  base::Closure dump_stack_;
-
  private:
   // The type this object is responsible for controlling.
   const ModelType type_;