Merge "In isTetheringSupported, call isAdmin user from system." am: 4a895309

        boolean tetherEnabledInSettings = (Settings.Global.getInt(mContext.getContentResolver(),

                Settings.Global.TETHER_SUPPORTED, defaultVal) != 0)

                && !mUserManager.hasUserRestriction(UserManager.DISALLOW_CONFIG_TETHERING);

        return tetherEnabledInSettings && mUserManager.isAdminUser() &&

        // Elevate to system UID to avoid caller requiring MANAGE_USERS permission.

        boolean adminUser = false;

        final long token = Binder.clearCallingIdentity();

        try {

            adminUser = mUserManager.isAdminUser();

        } finally {

            Binder.restoreCallingIdentity(token);

        }

        return tetherEnabledInSettings && adminUser &&

               mTethering.hasTetherableConfiguration();

    }