Merge "Instead of asserting, gracefully abort and signal and error."

        bool firstTime = (mPlaylist == NULL);

        mPlaylist = fetchPlaylist(url.c_str());

        CHECK(mPlaylist != NULL);

        if (mPlaylist == NULL) {

            LOGE("failed to load playlist at url '%s'", url.c_str());

            mDataSource->queueEOS(ERROR_IO);

            return;

        }

        if (firstTime) {

            Mutex::Autolock autoLock(mLock);

    sp<ABuffer> buffer;

    status_t err = fetchFile(uri.c_str(), &buffer);

    CHECK_EQ(err, (status_t)OK);

    if (err != OK) {

        LOGE("failed to fetch .ts segment at url '%s'", uri.c_str());

        mDataSource->queueEOS(err);

        return;

    }

    CHECK_EQ((status_t)OK,

             decryptBuffer(mSeqNumber - firstSeqNumberInPlaylist, buffer));