Once
https://crrev.com/c/4214978 lands WebAppFrameToolbarView (the three-dot menu, extension icon, reload button, etc) as well as the title for PWA windows will no longer be a child of BrowserNonClientFrameView, but rather become a child of BrowserView itself. This should cause nearly no noticeable changes, but helps unblocking "immersive fullscreen" mode on Mac OS for PWA windows.
Also my hope is that by doing the layout of the PWA titlebar as part of the rest of BrowserViewLayout there should be less code duplication between all the different platforms (as one example, with this change the under-development tabbed PWA mode should look and work a lot better on non-Chrome OS platforms).
I think I've tested the new implementation fairly well, but I wouldn't be surprised if I missed something, so please let me know if you see any strange rendering/behavior issues surrounding the PWA title/toolbar area, and I'll try to fix those (or worst case flip the flag back off while I figure out how to fix them).
Marijn