On Win 10, the OS window manager provides drag handles outside the left, bottom, and right edges of the window, but the top drag handle is inside the titlebar.  Chrome doesn't have a true titlebar, and in refresh, using the region above the tabs as both resize and drag handle is cramped.

Ideally, we would behave like CrOS and place the resize handle outside the top window edge.  Visual Studio also does this.  To achieve this:

* Create a separate HWND with WS_POPUP, WS_EX_TOOLWINDOW, WS_EX_LAYERED, all client area, painted with RGBA 0, 0, 0, 1
* Size this window to be the full main window width and 8 DIP tall minus the size of the stroke at the top of the Chrome window (this matches native behavior)
* Keep this window positioned above the main window at all times
* Use the full area above the tabs (except the stroke) as a drag handle

This sounds reasonably complicated to achieve (especially keeping the window positions in sync), so my time estimate may be off.