class VideoFrame

Releases the write lock on the buffer, and returns information

for transmitting that a frame is available for consumption.

This should only be called when ProcessPayload indicates

the frame is complete.

The returned FrameAvailableEvent accounts for frame errors, or if we didn't have a buffer.

Release will only return an error if there was a logical issue with the frame,

in which case the frame should not be sent to the stream client.

Both the UsbState and the VmoPool which produced the buffer passed to VideoFrame

must be valid for the lifetime of the frame.

Extracts the payload data from the usb request response,

and stores it in the video buffer.

Returns:

ZX_ERR_STOP - If the video frame has been completed by

this request. Release() can now be called.

ZX_ERR_NEXT - If the video frame has already been completed.

A new video frame should be created, and the

usb_request given should be passed to the new

frame.

ZX_OK - The data in the request was added to the frame.

Other Errors- There is an error with the request or the frame.

No action needs to be taken. Although this frame

will have errors, it is still necessary to wait until

a new frame is started. The error flag will be set

for this frame when Release is called.