diff -r 000000000000 -r 6474c204b198 xpcom/threads/nsIEventTarget.idl
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/xpcom/threads/nsIEventTarget.idl	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,64 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim:set ts=2 sw=2 sts=2 et cindent: */
+/* 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/. */
+
+#include "nsISupports.idl"
+
+interface nsIRunnable;
+
+[scriptable, uuid(4e8febe4-6631-49dc-8ac9-308c1cb9b09c)]
+interface nsIEventTarget : nsISupports
+{
+  /**
+   * Dispatch an event to this event target.  This function may be called from
+   * any thread, and it may be called re-entrantly.
+   *
+   * @param event
+   *   The event to dispatch.
+   * @param flags
+   *   The flags modifying event dispatch.  The flags are described in detail
+   *   below.
+   * 
+   * @throws NS_ERROR_INVALID_ARG
+   *   Indicates that event is null.
+   * @throws NS_ERROR_UNEXPECTED
+   *   Indicates that the thread is shutting down and has finished processing
+   * events, so this event would never run and has not been dispatched. 
+   */
+  void dispatch(in nsIRunnable event, in unsigned long flags);
+
+  /**
+   * This flag specifies the default mode of event dispatch, whereby the event
+   * is simply queued for later processing.  When this flag is specified,
+   * dispatch returns immediately after the event is queued.
+   */
+  const unsigned long DISPATCH_NORMAL = 0;
+
+  /**
+   * This flag specifies the synchronous mode of event dispatch, in which the
+   * dispatch method does not return until the event has been processed.
+   *
+   * NOTE: passing this flag to dispatch may have the side-effect of causing
+   * other events on the current thread to be processed while waiting for the
+   * given event to be processed.
+   */
+  const unsigned long DISPATCH_SYNC = 1;
+   
+  /**
+   * Check to see if this event target is associated with the current thread.
+   *
+   * @returns
+   *   A boolean value that if "true" indicates that events dispatched to this
+   *   event target will run on the current thread (i.e., the thread calling
+   *   this method).
+   */
+  boolean isOnCurrentThread();
+};
+
+%{C++
+// convenient aliases:
+#define NS_DISPATCH_NORMAL nsIEventTarget::DISPATCH_NORMAL
+#define NS_DISPATCH_SYNC   nsIEventTarget::DISPATCH_SYNC
+%}