1 files changed, 24 insertions, 0 deletions
diff --git a/browser/extensions/screenshots/assertIsTrusted.js b/browser/extensions/screenshots/assertIsTrusted.js
new file mode 100644
index 0000000000..9065d8603b
--- /dev/null
+++ b/browser/extensions/screenshots/assertIsTrusted.js
@@ -0,0 +1,24 @@
+/* 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/. */
+
+/** For use with addEventListener, assures that any events have event.isTrusted set to true
+      https://developer.mozilla.org/en-US/docs/Web/API/Event/isTrusted
+    Should be applied *inside* catcher.watchFunction
+*/
+this.assertIsTrusted = function assertIsTrusted(handlerFunction) {
+  return function(event) {
+    if (!event) {
+      const exc = new Error("assertIsTrusted did not get an event");
+      exc.noPopup = true;
+      throw exc;
+    }
+    if (!event.isTrusted) {
+      const exc = new Error(`Received untrusted event (type: ${event.type})`);
+      exc.noPopup = true;
+      throw exc;
+    }
+    return handlerFunction.call(this, event);
+  };
+};
+null;