[Settings] Code refactor

Bug: 147338143
Test: build pass
Change-Id: Ib4a92f659ceda3584310591f706958a06ba5ab21
diff --git a/src/com/android/settings/Utils.java b/src/com/android/settings/Utils.java
index 2f198cf..9b257b6 100644
--- a/src/com/android/settings/Utils.java
+++ b/src/com/android/settings/Utils.java
@@ -372,7 +372,7 @@
     }
 
     public static boolean hasMultipleUsers(Context context) {
-        return ((UserManager) context.getSystemService(Context.USER_SERVICE))
+        return context.getSystemService(UserManager.class)
                 .getUsers().size() > 1;
     }
 
@@ -666,7 +666,7 @@
      * @throws SecurityException if the given userId does not belong to the current user group.
      */
     public static int enforceSameOwner(Context context, int userId) {
-        final UserManager um = UserManager.get(context);
+        final UserManager um = context.getSystemService(UserManager.class);
         final int[] profileIds = um.getProfileIdsWithDisabled(UserHandle.myUserId());
         if (ArrayUtils.contains(profileIds, userId)) {
             return userId;
@@ -686,7 +686,7 @@
      * Returns the user id of the credential owner of the given user id.
      */
     public static int getCredentialOwnerUserId(Context context, int userId) {
-        final UserManager um = UserManager.get(context);
+        final UserManager um = context.getSystemService(UserManager.class);
         return um.getCredentialOwnerProfile(userId);
     }
 
@@ -823,7 +823,8 @@
     }
 
     public static boolean isDemoUser(Context context) {
-        return UserManager.isDeviceInDemoMode(context) && UserManager.get(context).isDemoUser();
+        return UserManager.isDeviceInDemoMode(context)
+                && context.getSystemService(UserManager.class).isDemoUser();
     }
 
     public static ComponentName getDeviceOwnerComponent(Context context) {
@@ -1051,7 +1052,7 @@
         final boolean isWork = args != null ? args.getInt(ProfileSelectFragment.EXTRA_PROFILE)
                 == ProfileSelectFragment.ProfileType.WORK : false;
         if (FeatureFlagUtils.isEnabled(activity, FeatureFlags.PERSONAL_WORK_PROFILE)
-                && UserManager.get(activity).getUserProfiles().size() > 1
+                && activity.getSystemService(UserManager.class).getUserProfiles().size() > 1
                 && ProfileFragmentBridge.FRAGMENT_MAP.get(fragmentName) != null
                 && !isWork && !isPersonal) {
             f = Fragment.instantiate(activity, ProfileFragmentBridge.FRAGMENT_MAP.get(fragmentName),