Merge "libmedia: synchronize access to meta."

        data.writeInterfaceToken(BpMediaSource::getInterfaceDescriptor());

        status_t ret = remote()->transact(GETFORMAT, data, &reply);

        if (ret == NO_ERROR) {

            AutoMutex _l(mLock);

            mMetaData = MetaData::createFromParcel(reply);

            return mMetaData;

        }

    // NuPlayer passes pointers-to-metadata around, so we use this to keep the metadata alive

    // XXX: could we use this for caching, or does metadata change on the fly?

    sp<MetaData> mMetaData;

    // ensure synchronize access to mMetaData

    Mutex mLock;

    // Cache all IMemory objects received from MediaExtractor.

    // We gc IMemory objects that are no longer active (referenced by a MediaBuffer).