Reland "[Profiles] Use new colored default avatars for taskbar badges"

This is a reland of 6b7290b3

Compared to the original CL, the reland sticks more to the previous
behavior of AvatarMenu::GetImageForMenuButton(), it does not download
high res avatar. The only change in behavior is on Windows where it uses
2x built-in avatars instead of 1x avatars which is beneficial for the
large taskbar of Win10.

Original change's description:
> [Profiles] Use new colored default avatars for taskbar badges
>
> Recently, all logic around profile avatars has been integrated into
> ProfileAttributesEntry::GetAvatarIcon() incl. new features such as
> colored default avatars.
>
> This CL updates code that generates taskbar badges on Windows to
> delegate most of its logic to GetAvatarIcon(). Only the pieces needed
> for obtaining ImageLoadStatus remained in this code.
>
> The only behavioral change is for non-GAIA avatars: high-res /
> 2x windows old avatars are returned instead of low-res avatars. This
> means more downscaling is needed than before. This will be addressed
> by further CLs that will make GetAvatarIcon() respect preferred_size in
> more cases.
>
> Bug: 1122559
> Change-Id: I5eecc7c6647dc78f9ff92d74edb64214a48e8e63
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2514153


> Commit-Queue: Jan Krcal <jkrcal@chromium.org>
> Reviewed-by: David Roger <droger@chromium.org>
> Auto-Submit: Jan Krcal <jkrcal@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#824494}

Bug: 1122559
Change-Id: I5814c801165fde00bb20694561e5b94db0e12cbc
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2521735


Commit-Queue: Jan Krcal <jkrcal@chromium.org>
Auto-Submit: Jan Krcal <jkrcal@chromium.org>
Reviewed-by: David Roger <droger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#824901}