Adds testing infrastructure to web_ui_browsertest to support testing HtmlDialogs.

chrome/browser/ui/webui/html_dialog_ui.cc

Index: chrome/browser/ui/webui/html_dialog_ui.cc
diff --git a/chrome/browser/ui/webui/html_dialog_ui.cc b/chrome/browser/ui/webui/html_dialog_ui.cc
index fd3341a4bbe187646a511a3a239a7d6a266e4bbf..511c8e4300fe939b80da4520f4a611bd23472874 100644
--- a/chrome/browser/ui/webui/html_dialog_ui.cc
+++ b/chrome/browser/ui/webui/html_dialog_ui.cc
@@ -7,9 +7,11 @@
 #include "base/callback.h"
 #include "base/lazy_instance.h"
 #include "base/values.h"
+#include "chrome/common/chrome_notification_types.h"
 #include "content/browser/renderer_host/render_view_host.h"
 #include "content/browser/tab_contents/tab_contents.h"
 #include "content/common/bindings_policy.h"
+#include "content/common/notification_service.h"
 
 static base::LazyInstance<PropertyAccessor<HtmlDialogUIDelegate*> >
     g_html_dialog_ui_property_accessor(base::LINKER_INITIALIZED);
@@ -60,6 +62,11 @@ void HtmlDialogUI::RenderViewCreated(RenderViewHost* render_view_host) {
     (*it)->Attach(this);
     AddMessageHandler(*it);
   }
+
+  NotificationService::current()->Notify(
+      chrome::NOTIFICATION_HTML_DIALOG_SHOWN,
+      Source<HtmlDialogUI>(this),
+      NotificationService::NoDetails());
 }
 
 void HtmlDialogUI::OnDialogClosed(const ListValue* args) {