I hit an assert when I run web platform test drm-mp4-syntax-mediakeysession.html: xul.dll!mozilla::dom::MediaKeys::RejectPromise(unsigned int aId, nsresult aExceptionCode, const nsCString & aReason) Line 239 C++ xul.dll!mozilla::GMPCDMProxy::RejectPromise(unsigned int aId, nsresult aCode, const nsCString & aReason) Line 502 C++ xul.dll!mozilla::GMPCDMProxy::OnRejectPromise(unsigned int aPromiseId, nsresult aDOMException, const nsCString & aMsg) Line 658 C++ xul.dll!mozilla::RejectPromiseTask::Run() Line 116 C++ The problem is that we're calling MediaKeys::ConnectPendingPromiseIdWithToken() on the MediaKeySession::Load() path, but we actually don't need to; inside Load() we already know the session Id, and we've already removed the session from the list of pending sessions in Load(), so the assertion fails. We should not be calling MediaKeys::ConnectPendingPromiseIdWithToken() inside MediaKeySession::Load().

Comment on attachment 8803139 [details] Bug 1311848 - Don't call ConnectPendingPromiseIdWithToken in MediaKeySession::Load. https://reviewboard.mozilla.org/r/87364/#review86462

Pushed by cpearce@mozilla.com: https://hg.mozilla.org/integration/autoland/rev/255e360cf9be Don't call ConnectPendingPromiseIdWithToken in MediaKeySession::Load. r=kikuo

Landed 22 hours ago https://hg.mozilla.org/mozilla-central/rev/255e360cf9be