Merge "MountService: Check for failure to unmount when enabling UMS and fix reversed logic"

        String vs = getVolumeState(path);

        if (enable && vs.equals(Environment.MEDIA_MOUNTED)) {

            mUmsEnabling = enable; // Override for isUsbMassStorageEnabled()

            doUnmountVolume(path);

            int rc = doUnmountVolume(path);

            mUmsEnabling = false; // Clear override

            if (rc != StorageResultCode.OperationSucceeded) {

                Log.e(TAG, String.format("Failed to unmount before enabling UMS (%d)", rc));

                return rc;

            }

        }

        try {

    }

    private int doUnmountVolume(String path) {

        if (getVolumeState(path).equals(Environment.MEDIA_MOUNTED)) {

        if (!getVolumeState(path).equals(Environment.MEDIA_MOUNTED)) {

            return VoldResponseCode.OpFailedVolNotMounted;

        }