Right now it has type nsCOMPtr<nsIXPConnectJSObjectHolder>, which is archaic. This class is already cycle collected, so it is not be too hard to convert.

try: https://treeherder.mozilla.org/#/jobs?repo=try&revision=90778283f2ef1313ce31b6881d0848982b2ad5d0

Comment on attachment 8868266 [details] Bug 1365086, part 1 - Make nsMessageManagerScriptExecutor::GetGlobal return a JSObject pointer. https://reviewboard.mozilla.org/r/139850/#review143210 ::: dom/base/nsFrameMessageManager.h:370 (Diff revision 1) > public: > static void PurgeCache(); > static void Shutdown(); > - already_AddRefed<nsIXPConnectJSObjectHolder> GetGlobal() > + JSObject* GetGlobal() > { > - nsCOMPtr<nsIXPConnectJSObjectHolder> ref = mGlobal; > + return mGlobal->GetJSObject(); Is it guaranteed mGlobal is non-null here? I'd prefer a null check.

Comment on attachment 8868267 [details] Bug 1365086, part 2 - Add unlink method for nsMessageManagerScriptExecutor. https://reviewboard.mozilla.org/r/139852/#review143212

(In reply to Olli Pettay [:smaug] from comment #5) > Is it guaranteed mGlobal is non-null here? > I'd prefer a null check. That actually just goes away in a later patch. (mGlobal becomes a JSObject, and we just return it directly.)

Comment on attachment 8868268 [details] Bug 1365086, part 3 - Make nsMessageManagerScriptExecutor::mGlobal into a raw pointer. https://reviewboard.mozilla.org/r/139854/#review143214 Given that this changes black root marking a bit (XPCJSRuntime::TraceNativeBlackRoots), worth to check whether telemetry data around CC changes. ::: dom/base/nsFrameMessageManager.h:370 (Diff revision 1) > public: > static void PurgeCache(); > static void Shutdown(); > JSObject* GetGlobal() > { > - return mGlobal->GetJSObject(); > + return mGlobal; Ah, we change mGlobal here, so null check isn't needed.

Pushed by amccreight@mozilla.com: https://hg.mozilla.org/integration/autoland/rev/2ca54e1cbf46 part 1 - Make nsMessageManagerScriptExecutor::GetGlobal return a JSObject pointer. r=smaug https://hg.mozilla.org/integration/autoland/rev/61d7468cd1c1 part 2 - Add unlink method for nsMessageManagerScriptExecutor. r=smaug https://hg.mozilla.org/integration/autoland/rev/d4e14b275a0f part 3 - Make nsMessageManagerScriptExecutor::mGlobal into a raw pointer. r=smaug

https://hg.mozilla.org/mozilla-central/rev/2ca54e1cbf46 https://hg.mozilla.org/mozilla-central/rev/61d7468cd1c1 https://hg.mozilla.org/mozilla-central/rev/d4e14b275a0f