[CrOS Tether] ProximityAuth WebUI improvement: show the local device's ID.

components/proximity_auth/webui/proximity_auth_webui_handler.h

Index: components/proximity_auth/webui/proximity_auth_webui_handler.h
diff --git a/components/proximity_auth/webui/proximity_auth_webui_handler.h b/components/proximity_auth/webui/proximity_auth_webui_handler.h
index 73221e1f7455b2de5b4bf468026f363f4d18e975..5fdc5b9e926c93b095faa951334080772c067933 100644
--- a/components/proximity_auth/webui/proximity_auth_webui_handler.h
+++ b/components/proximity_auth/webui/proximity_auth_webui_handler.h
@@ -120,6 +120,9 @@ class ProximityAuthWebUIHandler
   // MessengerObserver:
   void OnRemoteStatusUpdate(const RemoteStatusUpdate& status_update) override;
 
+  // Returns the truncated device ID of the local device.
+  std::unique_ptr<base::Value> GetTruncatedLocalDeviceId();
+
   // Returns the current enrollment state that can be used as a JSON object.
   std::unique_ptr<base::DictionaryValue> GetEnrollmentStateDictionary();