[ios] Fix Most Visited Tiles Module Placeholder bug

Bug: 1356996
Change-Id: I7e5f7edd43e2026d56b69195d8f347bc1b114f8b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3866752


Reviewed-by: Sebastien Seguin-Gagnon <sebsg@chromium.org>
Commit-Queue: Sebastien Seguin-Gagnon <sebsg@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1041705}