chromium/components/remote_cocoa/app_shim/native_widget_mac_overlay_nswindow.mm

// Copyright 2024 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#import "components/remote_cocoa/app_shim/native_widget_mac_overlay_nswindow.h"

#include <AppKit/AppKit.h>

// Overlay windows are used to render top chrome components while in immersive
// fullscreen. Those rendered views are hosted in a separate AppKit controlled
// window. The overlay windows are a transparent overlay on top of the AppKit
// hosted views, allowing for secondary UI to be aligned properly. Only allow
// `NSWindowCollectionBehaviorTransient` and
// `NSWindowCollectionBehaviorIgnoresCycle` to be set. Other collection
// behaviors can be problematic. In particular,
// `NSWindowCollectionBehaviorPrimary`, when set on an overlay window, can cause
// crashes. See https://crbug.com/348713769 for more info.
constexpr unsigned long kAllowedCollectionBehaviorMask =
    (NSWindowCollectionBehaviorTransient |
     NSWindowCollectionBehaviorIgnoresCycle);

@implementation NativeWidgetMacOverlayNSWindow

- (void)setCollectionBehavior:(NSWindowCollectionBehavior)collectionBehavior {
  [super setCollectionBehavior:collectionBehavior &
                               kAllowedCollectionBehaviorMask];
}

@end