FreeRTOS running, SUCCESS!
The function, USBD_CDC_ReceivePacket, is in usbd.cdc.c/h.
This function is called by CDC_Receive_FS in usbd_cdc_if.c.
The problem I have is understanding how CDC_Receive_FS gets called.
The code I am using to look into this is from the STM32CubeMX and STM32CubeF4.
I saw some other code as I looked around for more knowledge that appeared to have something akin to USBD_CDC_ReceivePacket running as a Thread in FreeRTOS, which made some sens to me, but, my knolwedge is limited.