assistant: delete empty methods

Bug: None
Test: compiles
Change-Id: I1adeaa38059ca097ea57ff9e9296f5a75d351e9e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2536691Reviewed-by: Yue Li <updowndota@chromium.org>
Reviewed-by: Jeroen Dhollander <jeroendh@chromium.org>
Commit-Queue: Xiaohui Chen <xiaohuic@chromium.org>
Cr-Commit-Position: refs/heads/master@{#827319}

chromeos/services/assistant/assistant_manager_service_impl.h

@@ -250,12 +250,6 @@ class COMPONENT_EXPORT(ASSISTANT_SERVICE) AssistantManagerServiceImpl
   void PostInitAssistant();
   bool IsServiceStarted() const;
 
-  // Update device id, type and locale
-  void UpdateDeviceSettings();
-
-  // Sync speaker id enrollment status.
-  void SyncSpeakerIdEnrollmentStatus();
-
   void HandleLaunchMediaIntentResponse(bool app_opened);
 
   void OnAlarmTimerStateChanged();