Fixing signin UI not being refreshed for proximity_auth.
Fixing signin UI not being refreshed for proximity_auth.

The auth attempt (user clicking the pod) was not being dispatched to
the |ProximityAuthSystem| during the sign in screen. This left
the UI stuck in the "Signing in..." state.

BUG=

Review URL: https://codereview.chromium.org/1386643003

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#352089}

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