Revert of Revert "Revert of Reland: Switch WindowedNotificationObserver to use base::RunLoop....

chrome/browser/ui/cocoa/apps/native_app_window_cocoa_browsertest.mm

Index: chrome/browser/ui/cocoa/apps/native_app_window_cocoa_browsertest.mm
diff --git a/chrome/browser/ui/cocoa/apps/native_app_window_cocoa_browsertest.mm b/chrome/browser/ui/cocoa/apps/native_app_window_cocoa_browsertest.mm
index 5f03bad8c78cf02daa952a1fca792fa4f54b0f2c..72b15bc2d24f0bebe3f0a7f34d50301df4326739 100644
--- a/chrome/browser/ui/cocoa/apps/native_app_window_cocoa_browsertest.mm
+++ b/chrome/browser/ui/cocoa/apps/native_app_window_cocoa_browsertest.mm
@@ -43,37 +43,6 @@
 
 namespace {
 
-class AppWindowObserver : public extensions::AppWindowRegistry::Observer {
- public:
-  AppWindowObserver(Profile* profile)
-      : registry_(extensions::AppWindowRegistry::Get(profile)) {
-    registry_->AddObserver(this);
-  }
-
-  ~AppWindowObserver() override { registry_->RemoveObserver(this); }
-
-  void Wait(int window_count) {
-    if (windows_added_count_ < window_count) {
-      windows_added_count_expected_ = window_count;
-      run_loop_.Run();
-    }
-  }
-
- private:
-  void OnAppWindowAdded(AppWindow* app_window) override {
-    ++windows_added_count_;
-    if (windows_added_count_expected_ > 0 &&
-        windows_added_count_ >= windows_added_count_expected_) {
-      run_loop_.Quit();
-    }
-  }
-
-  extensions::AppWindowRegistry* registry_;
-  int windows_added_count_ = 0;
-  int windows_added_count_expected_ = 0;
-  base::RunLoop run_loop_;
-};
-
 // The param selects whether to use ChromeNativeAppWindowViewsMac, otherwise it
 // will use NativeAppWindowCocoa.
 class NativeAppWindowCocoaBrowserTest
@@ -94,13 +63,15 @@
         test_data_dir_.AppendASCII("platform_apps").AppendASCII("minimal"), 1);
     EXPECT_TRUE(app_);
 
-    AppWindowObserver window_observer(profile());
     for (int i = 0; i < num_windows; ++i) {
+      content::WindowedNotificationObserver app_loaded_observer(
+          content::NOTIFICATION_LOAD_COMPLETED_MAIN_FRAME,
+          content::NotificationService::AllSources());
       OpenApplication(AppLaunchParams(
           profile(), app_, extensions::LAUNCH_CONTAINER_NONE,
           WindowOpenDisposition::NEW_WINDOW, extensions::SOURCE_TEST));
+      app_loaded_observer.Wait();
     }
-    window_observer.Wait(num_windows);
   }
 
   const extensions::Extension* app_;