Many of these interfaces are not intuitive, or are the way they are for
complex historical reasons, so it would be nice to document these things
for future developers.
Also, many nonstandard things (such as RTCConfiguration options) were
not documented at all before this CL.
BUG=webrtc:7131
TBR=pthatcher@webrtc.org
NOTRY=True
Review-Url: https://codereview.webrtc.org/2680273002
Cr-Commit-Position: refs/heads/master@{#16485}
The factory follows the same principles as PeerConnectionFactory;
various modules can be passed into its constructor but default
implementations are provided. Currently the only object the factory can
create is a UdpTransport (need to start somewhere).
UdpTransportChannel (renamed to UdpTransport)
will now accept a socket passed into its constructor,
relying on the factory to create the socket. This allows some
simplifications to be made, such as getting rid of "State" since the
only states are now "has destination set or doesn't".
BUG=webrtc:7013
Review-Url: https://codereview.webrtc.org/2632613002
Cr-Commit-Position: refs/heads/master@{#16154}
