Fixes a bug where popups were opened at the wrong size on OSX

This was caused because we weren't taking the title bar height into
account in BrowserNonClientFrameViewMac::GetWindowBoundsForClientBounds.

The fix is to explicitly add the titlebar size (which will be zero when
a custom titlebar is drawn) and GetTopInsets() to the client bounds when
converting them to window bounds.

This CL fixes a similar to
https://chromium-review.googlesource.com/c/chromium/src/+/1626909

Bug: 967935, 834908
Change-Id: I9fb6e537a86dc2babb567fdac14774787f0c5d97
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1657868
Reviewed-by: Elly Fong-Jones <ellyjones@chromium.org>
Reviewed-by: Leonard Grey <lgrey@chromium.org>
Commit-Queue: Jay Harris <harrisjay@chromium.org>
Cr-Commit-Position: refs/heads/master@{#669553}
2 files changed