We currently use the RemoteProtoChannel to send CompositorMessages from the renderer to the browser and then to the client. This is rigid since this ends up meaning that all our control/sync messages are buried inside cc protos.

As we pull out the sync protocol into blimp with the new split point, it would be better to use mojo for the renderer to/from browser IPCs and have the control messages be in blimp protos. This would also prepare the code for transitioning to helium easily.