From e4426ae30fce736981de9199dd67f9b9859ef811 Mon Sep 17 00:00:00 2001
From: Bill McCloskey <billm@mozilla.com>
Date: Sun, 13 Nov 2016 10:22:52 -0800
Subject: [PATCH] Bug 1318506 - Label AsyncEventDispatcher runnables with
 DocGroup (r=ehsan)

I still don't completely understand why we sometimes need to use the global
and sometimes the node. As far as I understand it:
- Not all event targets are nodes, so the node code can't always be used.
- The nsINode::GetOwnerGlobal implementation uses GetScriptHandlingObject,
  which returns null in some cases where GetScopeObject doesn't. Here
  is one:
    http://searchfox.org/mozilla-central/rev/62db1c9021cfbde9fa5e6e9601de16c21f4c7ce4/dom/base/nsDocument.cpp#4627

MozReview-Commit-ID: DdLWeQJIWZx
---
 dom/events/AsyncEventDispatcher.cpp | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/dom/events/AsyncEventDispatcher.cpp b/dom/events/AsyncEventDispatcher.cpp
index da36f7993900..a02d1a407ffb 100644
--- a/dom/events/AsyncEventDispatcher.cpp
+++ b/dom/events/AsyncEventDispatcher.cpp
@@ -66,6 +66,18 @@ nsresult
 AsyncEventDispatcher::PostDOMEvent()
 {
   RefPtr<AsyncEventDispatcher> ensureDeletionWhenFailing = this;
+  if (NS_IsMainThread()) {
+    if (nsCOMPtr<nsIGlobalObject> global = mTarget->GetOwnerGlobal()) {
+      return global->Dispatch("AsyncEvent", TaskCategory::Other, ensureDeletionWhenFailing.forget());
+    }
+
+    // Sometimes GetOwnerGlobal returns null because it uses
+    // GetScriptHandlingObject rather than GetScopeObject.
+    if (nsCOMPtr<nsINode> node = do_QueryInterface(mTarget)) {
+      nsCOMPtr<nsIDocument> doc = node->OwnerDoc();
+      return doc->Dispatch("AsyncEvent", TaskCategory::Other, ensureDeletionWhenFailing.forget());
+    }
+  }
   return NS_DispatchToCurrentThread(this);
 }