lacros: Use Chrome OS window sizing and placement logic

Refactor WindowSizerChromeOS to eliminate its dependency on
//chrome/browser/chromeos. Then link it into the lacros-chrome binary.

The primary user-visible change is that new browser window are
maximized on small displays, just like with chromeos-chrome.

There are two remaining issues:
- ForceMaximizeOnFirstRun policy support, crbug.com/1110548
- Wayland does not correctly report the display's work_area, so the
  restored bounds are incorrect, crbug.com/1110545

Bug: 1109050
Change-Id: I6209e61c1d606a722e66b146d9c62421b57adeb4
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2325256
Commit-Queue: James Cook <jamescook@chromium.org>
Reviewed-by: Michael Wasserman <msw@chromium.org>
Reviewed-by: Erik Chen <erikchen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#792940}