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This adds settings page to Ash HUD and makes HUT semi-transparent.

Just the HUD:
https://screenshot.googleplex.com/ZBqYnQDomH5.png

With the settings button:
https://screenshot.googleplex.com/pNCfTAw9J92.png

With settings UI displayed:
https://screenshot.googleplex.com/SwyNb0xVDbc.png

Bug: 1075612

Change-Id: I9f26e8b99f03e0d638f854312820f10ec25ee6a3
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2223974
Commit-Queue: Alexander Alekseev <alemate@chromium.org>
Reviewed-by: Mitsuru Oshima (slow:gardening) <oshima@chromium.org>
Cr-Commit-Position: refs/heads/master@{#780199}