feat: allow setting `roundedCorners` on Windows (#45740)

* feat: allow setting roundedCorners on Windows

Co-authored-by: Shelley Vohr <[email protected]>

* Update docs/api/structures/base-window-options.md

Co-authored-by: Will Anderson <[email protected]>

Co-authored-by: Shelley Vohr <[email protected]>

---------

Co-authored-by: trop[bot] <37223003+trop[bot]@users.noreply.github.com>
Co-authored-by: Shelley Vohr <[email protected]>

docs/api/structures/base-window-options.md

@@ -97,9 +97,10 @@
   * `height` Integer (optional) - The height of the title bar and Window Controls Overlay in pixels. Default is system height.
 * `trafficLightPosition` [Point](point.md) (optional) _macOS_ -
   Set a custom position for the traffic light buttons in frameless windows.
-* `roundedCorners` boolean (optional) _macOS_ - Whether frameless window
-  should have rounded corners on macOS. Default is `true`. Setting this property
-  to `false` will prevent the window from being fullscreenable.
+* `roundedCorners` boolean (optional) _macOS_ _Windows_ - Whether frameless window
+  should have rounded corners. Default is `true`. Setting this property
+  to `false` will prevent the window from being fullscreenable on macOS.
+  On Windows versions older than Windows 11 Build 22000 this property has no effect, and frameless windows will not have rounded corners.
 * `thickFrame` boolean (optional) - Use `WS_THICKFRAME` style for frameless windows on
   Windows, which adds standard window frame. Setting it to `false` will remove
   window shadow and window animations. Default is `true`.

shell/browser/native_window_views.cc

@@ -378,6 +378,11 @@ NativeWindowViews::NativeWindowViews(const gin_helper::Dictionary& options,
     if (!thick_frame_)
       frame_style &= ~(WS_THICKFRAME | WS_CAPTION);
     ::SetWindowLong(GetAcceleratedWidget(), GWL_STYLE, frame_style);
+
+    bool rounded_corner = true;
+    options.Get(options::kRoundedCorners, &rounded_corner);
+    if (!rounded_corner)
+      SetRoundedCorners(false);
   }
 
   LONG ex_style = ::GetWindowLong(GetAcceleratedWidget(), GWL_EXSTYLE);