MacViews: Implement Window-modal dialogs using sheets

ui/views/cocoa/views_nswindow_delegate.h

 // 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.
 
 #ifndef UI_VIEWS_COCOA_VIEWS_NSWINDOW_DELEGATE_H_
 #define UI_VIEWS_COCOA_VIEWS_NSWINDOW_DELEGATE_H_
 
 #import <Cocoa/Cocoa.h>
 
 #import "base/mac/scoped_nsobject.h"
@@ skipping 29 matching lines @@
 // Notify that the window has been reordered in (or removed from) the window
 // server's screen list. This is a substitute for -[NSWindowDelegate
 // windowDidExpose:], which is only sent for nonretained windows (those without
 // a backing store). |notification| is optional and can be set when redirecting
 // a notification such as NSApplicationDidHideNotification.
 - (void)onWindowOrderChanged:(NSNotification*)notification;
 
 // Notify when -[NSWindow display] is being called on the window.
 - (void)onWindowWillDisplay;
 
+// Called on the delegate of a modal sheet when its modal session ends.
+- (void)sheetDidEnd:(NSWindow*)sheet
+         returnCode:(NSInteger)returnCode
+        contextInfo:(void*)contextInfo;
+
 @end
 
 #endif  // UI_VIEWS_COCOA_VIEWS_NSWINDOW_DELEGATE_H_