Emit OnNativeWidgetDestroying() before clearing the NSWindowDelegate.

ui/views/cocoa/bridged_native_widget.mm

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #import "ui/views/cocoa/bridged_native_widget.h"
 
 #import <objc/runtime.h>
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 689 matching lines @@
   // called via ~CocoaMouseCapture() upon the destruction of |mouse_capture_|.
   // See crbug.com/622201. Also we do this before setting the delegate to nil,
   // because this may lead to callbacks to bridge which rely on a valid
   // delegate.
   ReleaseCapture();
 
   if (parent_) {
     parent_->RemoveChildWindow(this);
     parent_ = nullptr;
   }
-  [window_ setDelegate:nil];
   [[NSNotificationCenter defaultCenter] removeObserver:window_delegate_];
   native_widget_mac_->OnWindowWillClose();

[tapted, 2016/10/06 08:36:05]

Since it's convention to clear the delegate in -windowWillClose:, this needs a
comment above like

  // Note this also clears the NSWindow delegate, after informing Widget
  // delegates about the closure. NativeWidgetMac then deletes |this| before
  // returning.

[yamaxim, 2016/10/06 09:33:09]

done

 }
 
 void BridgedNativeWidget::OnFullscreenTransitionStart(
     bool target_fullscreen_state) {
   // Note: This can fail for fullscreen changes started externally, but a user
   // shouldn't be able to do that if the window is invisible to begin with.
   DCHECK(window_visible_);
 
   DCHECK_NE(target_fullscreen_state, target_fullscreen_state_);
   target_fullscreen_state_ = target_fullscreen_state;
@@ skipping 667 matching lines @@
   [bridged_view_ setMouseDownCanMoveWindow:draggable];
   // AppKit will not update its cache of mouseDownCanMoveWindow unless something
   // changes. Previously we tried adding an NSView and removing it, but for some
   // reason it required reposting the mouse-down event, and didn't always work.
   // Calling the below seems to be an effective solution.
   [window_ setMovableByWindowBackground:NO];
   [window_ setMovableByWindowBackground:YES];
 }
 
 }  // namespace views