Prepare this channel for resuming. The request will not start until
asyncOpen or open is called. Calling resumeAt after open or asyncOpen
has been called has undefined behaviour.
During OnStartRequest, this channel will have a status of
NS_ERROR_NOT_RESUMABLE if the file cannot be resumed, eg because the
server doesn’t support this. This error may occur even if startPos
is 0, so that the front end can warn the user.
Similarly, the status of this channel during OnStartRequest may be
NS_ERROR_ENTITY_CHANGED, which indicates that the entity has changed,
as indicated by a changed entityID.
In both of these cases, no OnDataAvailable will be called, and
OnStopRequest will immediately follow with the same status code.
| startPos | the starting offset, in bytes, to use to download |
| entityID | information about the file, to match before obtaining the file. Pass an empty string to use anything. |
The entity id for this URI. Available after OnStartRequest.
@throw NS_ERROR_NOT_RESUMABLE if this load is not resumable.