1 files changed, 45 insertions, 0 deletions
diff --git a/devtools/shared/loader/DistinctSystemPrincipalLoader.sys.mjs b/devtools/shared/loader/DistinctSystemPrincipalLoader.sys.mjs
new file mode 100644
index 0000000000..06c33b8891
--- /dev/null
+++ b/devtools/shared/loader/DistinctSystemPrincipalLoader.sys.mjs
@@ -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/. */
+
+const { DevToolsLoader } = ChromeUtils.importESModule(
+  "resource://devtools/shared/loader/Loader.sys.mjs",
+  {
+    // `loadInDevToolsLoader` will import the loader in a special priviledged
+    // global created for DevTools, which will be reused as the shared global
+    // to load additional modules for the "DistinctSystemPrincipalLoader".
+    loadInDevToolsLoader: true,
+  }
+);
+
+// When debugging system principal resources (JSMs, chrome documents, ...)
+// We have to load DevTools actors in another system principal global.
+// That's mostly because of spidermonkey's Debugger API which requires
+// debuggee and debugger to be in distinct principals.
+//
+// We try to hold a single instance of this special loader via this API.
+//
+// @param requester object
+//        Object/instance which is using the loader.
+//        The same requester object should be passed to release method.
+let systemLoader = null;
+const systemLoaderRequesters = new Set();
+
+export function useDistinctSystemPrincipalLoader(requester) {
+  if (!systemLoader) {
+    systemLoader = new DevToolsLoader({
+      useDevToolsLoaderGlobal: true,
+    });
+    systemLoaderRequesters.clear();
+  }
+  systemLoaderRequesters.add(requester);
+  return systemLoader;
+}
+
+export function releaseDistinctSystemPrincipalLoader(requester) {
+  systemLoaderRequesters.delete(requester);
+  if (systemLoaderRequesters.size == 0) {
+    systemLoader.destroy();
+    systemLoader = null;
+  }
+}