Fix crash when user closes window prior to the "Confirm Install" prompt showing

chrome/browser/ui/views/extensions/extension_install_dialog_view_browsertest.cc

 // 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.
 
 #include "chrome/browser/ui/views/extensions/extension_install_dialog_view.h"
 
 #include "base/strings/utf_string_conversions.h"
 #include "chrome/browser/extensions/extension_browsertest.h"
 #include "chrome/browser/extensions/extension_icon_manager.h"
 #include "chrome/browser/extensions/extension_install_prompt.h"
@@ skipping 143 matching lines @@
  private:
   DISALLOW_COPY_AND_ASSIGN(ScrollbarTest);
 };
 
 ScrollbarTest::ScrollbarTest()
     : ExtensionInstallDialogViewTestBase(
           ExtensionInstallPrompt::PERMISSIONS_PROMPT) {
 }
 
 bool ScrollbarTest::IsScrollbarVisible() {
-  ExtensionInstallPrompt::ShowParams show_params(web_contents());
   ExtensionInstallDialogView* dialog = new ExtensionInstallDialogView(
-      show_params.profile,
-      show_params.parent_web_contents,
+      profile(),
+      web_contents(),
       delegate(),
       prompt());
 
   // Create the modal view around the install dialog view.
   views::Widget* modal =
-      CreateBrowserModalDialogViews(dialog, show_params.parent_window);
+      CreateBrowserModalDialogViews(dialog,
+                                    web_contents()->GetTopLevelNativeWindow());
   modal->Show();
   content::RunAllBlockingPoolTasksUntilIdle();
 
   // Check if the vertical scrollbar is visible.
   return dialog->scroll_view()->vertical_scroll_bar()->visible();
 }
 
 // Tests that a scrollbar _is_ shown for an excessively long extension
 // install prompt.
 IN_PROC_BROWSER_TEST_F(ScrollbarTest, LongPromptScrollbar) {
@@ skipping 76 matching lines @@
     MockExtensionInstallPromptDelegate delegate;
     scoped_ptr<ExtensionInstallDialogView> dialog(
         new ExtensionInstallDialogView(
             profile(), web_contents(), &delegate, prompt()));
     dialog.reset();
 
     EXPECT_EQ(1, delegate.abort_count());
     EXPECT_EQ(0, delegate.proceed_count());
   }
 }