Allow WebUI Tests to use preLoad in HtmlDialogUI.

chrome/test/base/test_html_dialog_observer.h

 // Copyright (c) 2011 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_TEST_BASE_TEST_HTML_DIALOG_OBSERVER_H_
 #define CHROME_TEST_BASE_TEST_HTML_DIALOG_OBSERVER_H_
 #pragma once
 
 #include "base/compiler_specific.h"
 #include "content/public/browser/notification_observer.h"
 #include "content/public/browser/notification_registrar.h"
 
+class JsInjectionReadyObserver;
 class WebUI;
 
 // For browser_tests, which run on the UI thread, run a second message
 // MessageLoop to detect HtmlDialog creation and quit when the constructed
 // WebUI instance is captured and ready.
 class TestHtmlDialogObserver : public content::NotificationObserver {
  public:
-  // Create and register a new TestHtmlDialogObserver.
-  TestHtmlDialogObserver();
+  // Create and register a new TestHtmlDialogObserver. If
+  // |js_injection_ready_observer| is non-NULL, notify it as soon as the RVH is
+  // available.
+  explicit TestHtmlDialogObserver(
+      JsInjectionReadyObserver* js_injection_ready_observer);
   virtual ~TestHtmlDialogObserver();
 
   // Waits for an HtmlDialog to be created. The WebUI instance is captured
   // and the method returns it when the navigation on the dialog is complete.
   WebUI* GetWebUI();
 
  private:
   // content::NotificationObserver:
   virtual void Observe(int type, const content::NotificationSource& source,
                        const content::NotificationDetails& details) OVERRIDE;
 
   content::NotificationRegistrar registrar_;
 
+  // Observer to take some action when the dialog is ready for JavaScript
+  // injection.
+  JsInjectionReadyObserver* js_injection_ready_observer_;
   WebUI* web_ui_;
   bool done_;
   bool running_;
 
   DISALLOW_COPY_AND_ASSIGN(TestHtmlDialogObserver);
 };
 
 #endif  // CHROME_TEST_BASE_TEST_HTML_DIALOG_OBSERVER_H_