Adding pref to store the user-selected proximity threshold.

components/proximity_auth/proximity_auth_system.h

Index: components/proximity_auth/proximity_auth_system.h
diff --git a/components/proximity_auth/proximity_auth_system.h b/components/proximity_auth/proximity_auth_system.h
index 980f7fc0766c076b079b2774ef3f2547244e1c14..5bab44f13cf9f3a0aaa7d727f60dfd8c503b9f77 100644
--- a/components/proximity_auth/proximity_auth_system.h
+++ b/components/proximity_auth/proximity_auth_system.h
@@ -113,15 +113,15 @@ class ProximityAuthSystem : public RemoteDeviceLifeCycle::Observer,
   // the RemoteDevice of the currently focused user.
   std::unique_ptr<RemoteDeviceLifeCycle> remote_device_life_cycle_;
 
-  // Handles the interaction with the lock screen UI.
-  std::unique_ptr<UnlockManager> unlock_manager_;
-
   // Used to get the current timestamp.
   std::unique_ptr<base::Clock> clock_;
 
   // Fetches EasyUnlock preferences.
   std::unique_ptr<ProximityAuthPrefManager> pref_manager_;
 
+  // Handles the interaction with the lock screen UI.
+  std::unique_ptr<UnlockManager> unlock_manager_;
+
   // True if the system is suspended.
   bool suspended_;