Message “senders” have a single “other side” to which messages are
sent. For example, a child-process message manager will send
messages that are only delivered to its one parent-process message
manager.
Send |messageName| and |obj| to the “other side” of this message
manager. This invokes listeners who registered for
|messageName|.
See nsIMessageListener::receiveMessage() for the format of the
data delivered to listeners.
@throws NS_ERROR_NOT_INITIALIZED if the sender is not initialized. For
example, we will throw NS_ERROR_NOT_INITIALIZED if we try to send
a message to a cross-process frame but the other process has not
yet been set up.
@throws NS_ERROR_FAILURE when the message receiver cannot be found. For
example, we will throw NS_ERROR_FAILURE if we try to send a message
to a cross-process frame whose process has crashed.