ozone/wayland: Allow to rebind the interface.

Clients may want to rebind the interface and destroy previous
connections. However, there can be a race when doing so.

For example, when GpuProcessHost dies, it reroutes the call to
OnChannelDestroyed to the UI thread via PostTask, which may arrive
later than OnGpuServiceLaunched. This particular problem may
happen when something goes wrong with the gpu process.

Fuchsia does the same. Thus, I think it's ok to do so in
Wayland as well.

Bug: 578890
Change-Id: I725893021fe2485d4709e25005f68122b0d77297
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2135628
Commit-Queue: Maksim Sisov <msisov@igalia.com>
Reviewed-by: Robert Kroeger <rjkroege@chromium.org>
Cr-Commit-Position: refs/heads/master@{#757357}