[Reland] Enable AutoResize for Constrained Web Dialogs for Mac.

chrome/browser/ui/cocoa/constrained_window/constrained_window_web_dialog_sheet.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 CHROME_BROWSER_UI_COCOA_CONSTRAINED_WINDOW_CONSTRAINED_WINDOW_WEB_DIALOG_SHEET_H_
 #define CHROME_BROWSER_UI_COCOA_CONSTRAINED_WINDOW_CONSTRAINED_WINDOW_WEB_DIALOG_SHEET_H_
 
 #import "chrome/browser/ui/cocoa/constrained_window/constrained_window_custom_sheet.h"
 
 namespace ui {
 class WebDialogDelegate;
 }
 
 // Represents a custom sheet for web dialog.
 @interface WebDialogConstrainedWindowSheet : CustomConstrainedWindowSheet {
  @private
+  NSSize current_size_;
   ui::WebDialogDelegate* web_dialog_delegate_;  // Weak.
 }
 
 - (id)initWithCustomWindow:(NSWindow*)customWindow
          webDialogDelegate:(ui::WebDialogDelegate*)delegate;
 
 @end
 
 #endif  // CHROME_BROWSER_UI_COCOA_CONSTRAINED_WINDOW_CONSTRAINED_WINDOW_WEB_DIALOG_SHEET_H_