[CR2023] Fix Textfield hover when selected.

After pressing on a Textfield, the background hover should disappear. Since Inkdrop doesn't support this, delegate to the Textfield's `OnMousePressed` to set the Inkdrop's hover state.

Bug: 1400023
Change-Id: Ifab313d2f23c9ba8ff9acccf98b8837d7bf4cc7b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4642260


Commit-Queue: David Yeung <dayeung@chromium.org>
Reviewed-by: Elaine Chien <elainechien@chromium.org>
Code-Coverage: Findit <findit-for-me@appspot.gserviceaccount.com>
Cr-Commit-Position: refs/heads/main@{#1162685}