1 files changed, 63 insertions, 0 deletions
diff --git a/devtools/shared/performance-new/recording-utils.js b/devtools/shared/performance-new/recording-utils.js
new file mode 100644
index 0000000000..bbae0449fd
--- /dev/null
+++ b/devtools/shared/performance-new/recording-utils.js
@@ -0,0 +1,63 @@
+/* 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/. */
+// @ts-check
+"use strict";
+
+/**
+ * This file is for the new performance panel that targets profiler.firefox.com,
+ * not the default-enabled DevTools performance panel.
+ */
+
+/**
+ * @typedef {import("../../client/performance-new/@types/perf").GetActiveBrowsingContextID} GetActiveBrowsingContextID
+ */
+
+/**
+ * TS-TODO
+ *
+ * This function replaces lazyRequireGetter, and TypeScript can understand it. It's
+ * currently duplicated until we have consensus that TypeScript is a good idea.
+ *
+ * @template T
+ * @type {(callback: () => T) => () => T}
+ */
+function requireLazy(callback) {
+  /** @type {T | undefined} */
+  let cache;
+  return () => {
+    if (cache === undefined) {
+      cache = callback();
+    }
+    return cache;
+  };
+}
+
+const lazyServices = requireLazy(() =>
+  require("resource://gre/modules/Services.jsm")
+);
+
+/**
+ * Gets the ID of active BrowsingContext from the browser.
+ *
+ * @type {GetActiveBrowsingContextID}
+ */
+function getActiveBrowsingContextID() {
+  const { Services } = lazyServices();
+  const win = Services.wm.getMostRecentWindow("navigator:browser");
+
+  if (win?.gBrowser?.selectedBrowser?.browsingContext?.id) {
+    return win.gBrowser.selectedBrowser.browsingContext.id;
+  }
+
+  console.error(
+    "Failed to get the active BrowsingContext ID while starting the profiler."
+  );
+  // `0` mean that we failed to ge the active BrowsingContext ID, and it's
+  // treated as null value in the platform.
+  return 0;
+}
+
+module.exports = {
+  getActiveBrowsingContextID,
+};