Allow WebUI Tests to use preLoad in HtmlDialogUI.

chrome/test/base/test_html_dialog_observer.h

Index: chrome/test/base/test_html_dialog_observer.h
diff --git a/chrome/test/base/test_html_dialog_observer.h b/chrome/test/base/test_html_dialog_observer.h
index 795923447b370ce50f88adf0251fea4ee0216a5a..b3d6caa3b583d8a428ea6c9ed8ba3364ce9be26d 100644
--- a/chrome/test/base/test_html_dialog_observer.h
+++ b/chrome/test/base/test_html_dialog_observer.h
@@ -10,6 +10,7 @@
 #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
@@ -17,8 +18,11 @@ class WebUI;
 // 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
@@ -32,6 +36,7 @@ class TestHtmlDialogObserver : public content::NotificationObserver {
 
   content::NotificationRegistrar registrar_;
 
+  JsInjectionReadyObserver* js_injection_ready_observer_;
   WebUI* web_ui_;
   bool done_;
   bool running_;