1 files changed, 45 insertions, 0 deletions
diff --git a/devtools/client/responsive/utils/window.js b/devtools/client/responsive/utils/window.js
new file mode 100644
index 0000000000..927ff8570c
--- /dev/null
+++ b/devtools/client/responsive/utils/window.js
@@ -0,0 +1,45 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+const Services = require("Services");
+
+/**
+ * Returns the `nsIDOMWindow` toplevel window for any child/inner window
+ */
+function getTopLevelWindow(window) {
+  return window.browsingContext.topChromeWindow;
+}
+exports.getTopLevelWindow = getTopLevelWindow;
+
+function getDOMWindowUtils(window) {
+  return window.windowUtils;
+}
+exports.getDOMWindowUtils = getDOMWindowUtils;
+
+/**
+ * Check if the given browser window has finished the startup.
+ * @params {nsIDOMWindow} window
+ */
+const isStartupFinished = window => window.gBrowserInit?.delayedStartupFinished;
+
+function startup(window) {
+  return new Promise(resolve => {
+    if (isStartupFinished(window)) {
+      resolve(window);
+      return;
+    }
+    Services.obs.addObserver(function listener({ subject }) {
+      if (subject === window) {
+        Services.obs.removeObserver(
+          listener,
+          "browser-delayed-startup-finished"
+        );
+        resolve(window);
+      }
+    }, "browser-delayed-startup-finished");
+  });
+}
+exports.startup = startup;