class Receive

Receives at least `requested` bytes of data from the USB fastboot device.

Upon success, a vmo is allocated and returned by the driver which contains the data and the

actual received data size (via vmo::get_prop_content_size()). Because USB transmission is

in the unit of packet (512bytes), the actual received size can be at most 512 bytes more

than the requested size.

If `requested` is 0, the driver returns as soon as a USB packet with data is received. This

should be the value used when expecting fastboot command which is guaranteed to be within a

single USB packet (a fastboot command is no more than 64 bytes as per protocol). When

expecting larger amount of data during image download, it should be set to a larger value

to avoid the overhead of calling this FIDL too many times, as it can be very expensive

comparing to actual data transfer.

This FIDL protocol is blocking and can only serve one request at a time (Send() is not

affected. Receive() and Send() are individually synchronous).

Returns ZX_ERR_UNAVAILABLE if another call is made while a previous one is being processed,

or the FIDL is called too early during boot when the driver has not become ready.