views: ensure widget sublevels on activation

On Windows, the stacking levels among widgets are reset after the
browser regains activation using Alt+Tab, this causes widgets to be
misplaced in terms of their z-order sublevels. This patch fixes the
issue by re-ordering the entire widget tree when any widget in the tree
becomes active.

Bug: 345271842
Change-Id: If24f73c0d62701b973b50ef05f4ad462b5998601
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5622196


Code-Coverage: findit-for-me@appspot.gserviceaccount.com <findit-for-me@appspot.gserviceaccount.com>
Reviewed-by: Allen Bauer <kylixrd@chromium.org>
Commit-Queue: Keren Zhu <kerenzhu@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1314127}