Align favicon with the top of tab-title in the ShareThisTabDialog

This gives a more pleasing visual balance than vertically aligning
the center of the favicon with the center of the label. It is also
in agreement with the pre-existing layout of DesktopMediaSourceView.


Bug: 1428878
Change-Id: I954b04704b92e1fff40ad6db5d345fcfd3f28695
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4547816


Reviewed-by: Elad Alon <eladalon@chromium.org>
Commit-Queue: Tove Petersson <tovep@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1147405}