Merge "Change default value of preferredSubId from INVLAID to DEFAULT."

    // If mPreferredDataSubId is an active subscription, it overrides

    // mDefaultDataSubId and decides:

    // 1. In modem layer, which subscription is preferred to have data traffic on.

    // 2. In TelephonyNetworkFactory, which subscription will apply default network requets, which

    // 2. In TelephonyNetworkFactory, which subscription will apply default network requests, which

    //    are requests without specifying a subId.

    private int mPreferredDataSubId = SubscriptionManager.INVALID_SUBSCRIPTION_ID;

    private int mPreferredDataSubId = SubscriptionManager.DEFAULT_SUBSCRIPTION_ID;

    @VisibleForTesting

    // Corresponding phoneId after considerting mPreferredDataSubId and mDefaultDataSubId above.