[Extensions Refactor] Use extension id instead of view controller

Popped out action only needs to store the extension id to pop out/in
the action. There is no need to store a reference to the view
controller.

Bug: n/a
Change-Id: Ifc155137b3052797c4c5abc3e0ea202f9be2fc5b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4908418
Reviewed-by: Caroline Rising <corising@chromium.org>
Commit-Queue: Emilia Paz <emiliapaz@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1205933}