Merge "aaudio: allow AudioRecord to use FAST mode for TRANSFER_SYNC" into oc-dev

    // Client can only express a preference for FAST.  Server will perform additional tests.

    if (mFlags & AUDIO_INPUT_FLAG_FAST) {

        bool useCaseAllowed =

            // either of these use cases:

            // any of these use cases:

            // use case 1: callback transfer mode

            (mTransfer == TRANSFER_CALLBACK) ||

            // use case 2: obtain/release mode

            // use case 2: blocking read mode

            // The default buffer capacity at 48 kHz is 2048 frames, or ~42.6 ms.

            // That's enough for double-buffering with our standard 20 ms rule of thumb for

            // the minimum period of a non-SCHED_FIFO thread.

            // This is needed so that AAudio apps can do a low latency non-blocking read from a

            // callback running with SCHED_FIFO.

            (mTransfer == TRANSFER_SYNC) ||

            // use case 3: obtain/release mode

            (mTransfer == TRANSFER_OBTAIN);

        // sample rates must also match

        bool fastAllowed = useCaseAllowed && (mSampleRate == afSampleRate);