Handle multiple bindings.

Previously caused crash:
binding_state.cc(90)] Check failed: !is_bound(). Attempting to bind
interface that is already bound: ash::mojom::AssistantController.

Bug: b:79936619
Change-Id: I8c2bcb00becf0d9dd637bfe855053e14b21df0bc
Reviewed-on: https://chromium-review.googlesource.com/1064540
Reviewed-by: Xiaohui Chen <[email protected]>
Reviewed-by: Xiyuan Xia <[email protected]>
Commit-Queue: David Black <[email protected]>
Cr-Commit-Position: refs/heads/master@{#559703}
2 files changed