Factor out uses of the WebContentsModalDialog interface from platform-independent code

chrome/browser/ui/webui/constrained_web_dialog_ui_browsertest.cc

 // 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.
 
 #include "chrome/test/ui/ui_test.h"
 
 #include "base/utf_string_conversions.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/ui/browser.h"
 #include "chrome/browser/ui/tabs/tab_strip_model.h"
@@ skipping 52 matching lines @@
   WebContents* web_contents =
       browser()->tab_strip_model()->GetActiveWebContents();
   ASSERT_TRUE(web_contents);
 
   ConstrainedWebDialogDelegate* dialog_delegate =
       CreateConstrainedWebDialog(browser()->profile(),
                                  delegate,
                                  NULL,
                                  web_contents);
   ASSERT_TRUE(dialog_delegate);
-  EXPECT_TRUE(dialog_delegate->GetWindow());
+  EXPECT_TRUE(dialog_delegate->GetNativeDialog());
   EXPECT_TRUE(IsShowingWebContentsModalDialog(web_contents));
 }
 
 // Tests that ReleaseWebContentsOnDialogClose() works.
 IN_PROC_BROWSER_TEST_F(ConstrainedWebDialogBrowserTest,
                        ReleaseWebContentsOnDialogClose) {
   // The delegate deletes itself.
   WebDialogDelegate* delegate = new ui::test::TestWebDialogDelegate(
       GURL(chrome::kChromeUIConstrainedHTMLTestURL));
   WebContents* web_contents =
@@ skipping 12 matching lines @@
 
   ConstrainedWebDialogBrowserTestObserver observer(new_tab.get());
   dialog_delegate->ReleaseWebContentsOnDialogClose();
   dialog_delegate->OnDialogCloseFromWebUI();
 
   ASSERT_FALSE(observer.contents_destroyed());
   EXPECT_FALSE(IsShowingWebContentsModalDialog(web_contents));
   new_tab.reset();
   EXPECT_TRUE(observer.contents_destroyed());
 }