[ios] Fix Showcase

Remove reference to classes that now longer exists (they were removed
in https://crrev.com/c/1015541 and https://crrev.com/c/2053516). Add
a DCHECK that all classes registered in -[Showcase model] exists to
catch those errors next time.

Bug: none
Change-Id: I35d250257a7342e0f7561df65ee0bba7db4ecd38
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2844578
Commit-Queue: Sylvain Defresne <sdefresne@chromium.org>
Commit-Queue: Gauthier Ambard <gambard@chromium.org>
Auto-Submit: Sylvain Defresne <sdefresne@chromium.org>
Reviewed-by: Gauthier Ambard <gambard@chromium.org>
Cr-Commit-Position: refs/heads/master@{#875140}
GitOrigin-RevId: 81dfac6961cce7c1df7ee2623aa498ea79ce6933
1 file changed