Adds testing infrastructure to web_ui_browsertest to support testing HtmlDialogs.

chrome/test/test_html_dialog_observer.cc

Index: chrome/test/test_html_dialog_observer.cc
diff --git a/chrome/test/test_html_dialog_observer.cc b/chrome/test/test_html_dialog_observer.cc
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index 0000000000000000000000000000000000000000..90a75526bbab1ce54d58c7e0c471cfbe4dec7d69
--- /dev/null
+++ b/chrome/test/test_html_dialog_observer.cc
@@ -0,0 +1,63 @@
+// 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.
+
+#include "chrome/test/test_html_dialog_observer.h"
+
+#include "chrome/common/chrome_notification_types.h"
+#include "content/common/content_notification_types.h"
+#include "content/common/notification_details.h"
+#include "content/common/notification_service.h"
+#include "content/common/notification_source.h"
+#include "content/browser/tab_contents/navigation_controller.h"
+#include "content/browser/tab_contents/tab_contents.h"
+#include "content/browser/webui/web_ui.h"
+#include "chrome/test/base/ui_test_utils.h"
+
+TestHtmlDialogObserver::TestHtmlDialogObserver()
+    : web_ui_(NULL), done_(false), running_(false) {
+  registrar_.Add(this, chrome::NOTIFICATION_HTML_DIALOG_SHOWN,
+                 NotificationService::AllSources());
+}
+
+TestHtmlDialogObserver::~TestHtmlDialogObserver() {
+}
+
+void TestHtmlDialogObserver::Observe(int type,
+                                     const NotificationSource& source,
+                                     const NotificationDetails& details) {
+  switch (type) {
+    case chrome::NOTIFICATION_HTML_DIALOG_SHOWN:
+      web_ui_ = Source<WebUI>(source).ptr();
+      registrar_.Remove(this, chrome::NOTIFICATION_HTML_DIALOG_SHOWN,
+                        NotificationService::AllSources());
+      // Wait for navigation on the new WebUI instance to complete.

[Paweł Hajdan Jr., 2011/09/15 22:11:31]

This might be racy as commented on before. Please do either a convincing
analysis of the code or register for the notification at some earlier point.

By the way, I think it should be pretty easy to just register info about all
NavigationControllers and then match it to the WebUI instance. Watch out for ABA
issues though.

[flackr, 2011/09/16 15:44:00]

If I register for all NavigationControllers then I would have to keep a set of
which NavigationControllers I've observed as it is possible that a navigation
occurs for another tab and until NOTIFICATION_HTML_DIALOG_SHOWN is issued I
don't know which NavigationController to watch for.

I did an analysis of the code and found that the render view is created (and
notification delivered resulting in NOTIFICATION_HTML_DIALOG_SHOWN) before
navigation takes place so there is no race condition. Since the navigate method
is called on the new render view host this should continue to be the case in the
future.

NOTIFICATION_HTML_DIALOG_SHOWN is issued on creation of the RenderView which is
the first step taken in TabContents::NavigateToEntry:
http://codesearch.google.com/#OAMlx_jo-ck/src/content/browser/tab_contents/ta...

Later in that method the newly created RenderViewHost is told to navigate:
http://codesearch.google.com/#OAMlx_jo-ck/src/content/browser/tab_contents/ta...

[Paweł Hajdan Jr., 2011/09/19 17:48:12]

Excellent. Could you please add the most important parts of that analysis to the
comment in the code? It would be very helpful when debugging in case the
behavior of TabContents changes.

[flackr, 2011/09/20 14:16:17]

Done. Hopefully it's not too wordy.

+      registrar_.Add(this, content::NOTIFICATION_LOAD_STOP,
+                     Source<NavigationController>(
+                         &web_ui_->tab_contents()->controller()));
+      break;
+    case content::NOTIFICATION_LOAD_STOP:
+      DCHECK(web_ui_);
+      registrar_.Remove(this, content::NOTIFICATION_LOAD_STOP,
+                        Source<NavigationController>(
+                            &web_ui_->tab_contents()->controller()));
+      done_ = true;
+      // If the message loop is running stop it.
+      if (running_) {
+        running_ = false;
+        MessageLoopForUI::current()->Quit();
+      }
+      break;
+    default:
+      NOTREACHED();
+  };
+}
+
+WebUI* TestHtmlDialogObserver::GetWebUI() {
+  if (!done_) {
+    EXPECT_FALSE(running_);
+    running_ = true;
+    ui_test_utils::RunMessageLoop();
+  }
+  return web_ui_;
+}