Ensure proper rendering of scrolled Omnibox content.

The change includes vertical scrolling position, ensuring scrolling
content of the multiline Omnibox to be rendered when more than 5 lines
of text are entered.

Change-Id: I5ba9a2d29714b5c4a391a747d7f7f82703d14748
Fixed: 445570202
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6966027
Reviewed-by: Patrick Noland <pnoland@chromium.org>
Commit-Queue: Tomasz Wiszkowski <ender@google.com>
Cr-Commit-Position: refs/heads/main@{#1517539}