[UI] Make auto-resizable constrained web dialog work even when initiated

components/constrained_window/constrained_window_views.h

 // Copyright (c) 2012 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 COMPONENTS_CONSTRAINED_WINDOW_CONSTRAINED_WINDOW_VIEWS_H_
 #define COMPONENTS_CONSTRAINED_WINDOW_CONSTRAINED_WINDOW_VIEWS_H_
 
 #include <memory>
 
 #include "ui/gfx/native_widget_types.h"
@@ skipping 24 matching lines @@
 // Update the position of dialog |widget| against |dialog_host|. This is used to
 // reposition widgets e.g. when the host dimensions change.
 void UpdateWebContentsModalDialogPosition(
     views::Widget* widget,
     web_modal::WebContentsModalDialogHost* dialog_host);
 
 void UpdateWidgetModalDialogPosition(
     views::Widget* widget,
     web_modal::ModalDialogHost* dialog_host);
 
+// Returns the top level WebContents of |initiator_web_contents|.
+content::WebContents* GetTopLevelWebContents(
+    content::WebContents* initiator_web_contents);
+
 // Shows the dialog with a new SingleWebContentsDialogManager. The dialog will
 // notify via WillClose() when it is being destroyed.
 void ShowModalDialog(gfx::NativeWindow dialog,
                      content::WebContents* web_contents);
 
 // Calls CreateWebModalDialogViews, shows the dialog, and returns its widget.
 views::Widget* ShowWebModalDialogViews(
     views::WidgetDelegate* dialog,
     content::WebContents* initiator_web_contents);
 
@@ skipping 15 matching lines @@
 // Create a widget for |dialog| that has a modality given by
 // |dialog->GetModalType()|.  The modal type must be either
 // ui::MODAL_TYPE_SYSTEM or ui::MODAL_TYPE_WINDOW.  This places the
 // dialog appropriately if |parent| is a valid browser window.
 views::Widget* CreateBrowserModalDialogViews(views::DialogDelegate* dialog,
                                              gfx::NativeWindow parent);
 
 }  // namespace constrained_window
 
 #endif  // COMPONENTS_CONSTRAINED_WINDOW_CONSTRAINED_WINDOW_VIEWS_H_