The new `will-resize` event can be used to prevent the resize from
happening before the native window is actually resized. This is in
contrast to the existing the `resize` event, which is sent *after* the
native window has already been resized. For apps with e.g. custom window
snapping logic, the `resize` event is not sufficient because it will
result in flickering between the dragged size and the snapped size.
`will-resize` is only emitted on macOS and Windows.
Fixes#12701 and supersedes #13131.
Ideally we would have added `setTitleBarStyle()`, but that is a
significantly more involved change. For example, consider the case where
we switch from `hidden` to `normal`. We would not only have to show the
traffic light buttons, we would also have to switch the window from a
frameless to a framed window and deal with various other window state.
Lets instead implement a simple solution for #12701.
* Add atom::api::TopLevelWindow
* Make BrowserWindow inherit TopLevelWindow
* Fix reading from wrong weak map
* Read options after setting content view
* OnWindowClosed is not guarenteed to run now
* Fix the offscreen hack in BrowserWindow
* Fix building on Linux
* Fix tests on Linux
* Fix building on Windows
