[WebModals] New API for browser-scoped popup management.

apps/app_window.cc

Index: apps/app_window.cc
diff --git a/apps/app_window.cc b/apps/app_window.cc
index 814d2e0ae82f470d9016b39b416201cc9098eb9a..2c64ab3747e626678c17148741f1345838125795 100644
--- a/apps/app_window.cc
+++ b/apps/app_window.cc
@@ -264,6 +264,7 @@ void AppWindow::Init(const GURL& url,
     content::WebContentsObserver::Observe(web_contents);
   }
   delegate_->InitWebContents(web_contents);
+
   WebContentsModalDialogManager::CreateForWebContents(web_contents);
   // TODO(jamescook): Delegate out this creation.
   extensions::ChromeExtensionWebContentsObserver::CreateForWebContents(
@@ -286,6 +287,11 @@ void AppWindow::Init(const GURL& url,
 
   native_app_window_.reset(delegate_->CreateNativeAppWindow(this, new_params));
 
+  DCHECK(GetWebContentsModalDialogHost());
+  popup_manager_.reset(
+      new web_modal::PopupManager(GetWebContentsModalDialogHost()));
+  popup_manager_->RegisterWith(web_contents);
+
   // Prevent the browser process from shutting down while this window exists.
   AppsClient::Get()->IncrementKeepAliveCount();
   UpdateExtensionAppIcon();