// listen for settings changes
        ContentResolver resolver = mContext.getContentResolver();
        Cursor settingsCursor = resolver.query(Settings.Secure.CONTENT_URI, null,
                "(" + Settings.System.NAME + "=?)",
                new String[]{Settings.Secure.LOCATION_PROVIDERS_ALLOWED},
                null);
        mSettings = new ContentQueryMap(settingsCursor, Settings.System.NAME, true, mLocationHandler);
        SettingsObserver settingsObserver = new SettingsObserver();
        mSettings.addObserver(settingsObserver);

        // listen for settings changes
        ContentResolver resolver = mContext.getContentResolver();
        Cursor settingsCursor = resolver.query(Settings.Secure.CONTENT_URI, null,
                "(" + Settings.System.NAME + "=?)",
                new String[]{Settings.Secure.LOCATION_PROVIDERS_ALLOWED},
                null);
        mSettings = new ContentQueryMap(settingsCursor, Settings.System.NAME, true, mLocationHandler);
        SettingsObserver settingsObserver = new SettingsObserver();
        mSettings.addObserver(settingsObserver);


...

    private final class SettingsObserver implements Observer {
        public void update(Observable o, Object arg) {
            synchronized (mLock) {
                updateProvidersLocked();
            }
        }
    }