Bug 1644647 reject promises for Close AudioContextOperations run after forced graph shutdown r=padenot

and re-enable OnStateChanged() transition assertions.

Rejecting the promise avoids having AudioContextOperation promises resolve out
of order when AudioContextOperationControlMessage::RunDuringShutdown()
resolves a Close operation shortly after Run() for a previous operation has
queued its update via mUpdateRunnables.  mUpdateRunnables are run after
controlMessagesToRunDuringShutdown.
https://searchfox.org/mozilla-central/rev/ea7f70dac1c5fd18400f6d2a92679777d4b21492/dom/media/MediaTrackGraph.cpp#1793,1803

AudioContext::Shutdown() takes care of rejecting JS Promises when the window
is being destroyed.

Differential Revision: https://phabricator.services.mozilla.com/D79055

dom/media/MediaTrackGraph.cpp

@@ -3433,7 +3433,7 @@ class AudioContextOperationControlMessage : public ControlMessage {
   void RunDuringShutdown() override {
     MOZ_ASSERT(mAudioContextOperation == AudioContextOperation::Close,
                "We should be reviving the graph?");
-    mHolder.Resolve(AudioContextState::Closed, __func__);
+    mHolder.Reject(false, __func__);
   }
 
   nsTArray<RefPtr<MediaTrack>> mTracks;

dom/media/webaudio/AudioContext.cpp

@@ -826,45 +826,13 @@ void AudioContext::Dispatch(already_AddRefed<nsIRunnable>&& aRunnable) {
 void AudioContext::OnStateChanged(void* aPromise, AudioContextState aNewState) {
   MOZ_ASSERT(NS_IsMainThread());
 
-  // This can happen if close() was called right after creating the
-  // AudioContext, before the context has switched to "running".
-  if (mAudioContextState == AudioContextState::Closed &&
-      aNewState == AudioContextState::Running && !aPromise) {
-    return;
-  }
-
-  // This can happen if this is called in reaction to a
-  // MediaTrackGraph shutdown, and a AudioContext was being
-  // suspended at the same time, for example if a page was being
-  // closed.
-  if (mAudioContextState == AudioContextState::Closed &&
-      aNewState == AudioContextState::Suspended) {
-    return;
-  }
-
-#ifndef WIN32  // Bug 1170547
-#  ifndef XP_MACOSX
-#    ifdef DEBUG
-
-  if (!((mAudioContextState == AudioContextState::Suspended &&
-         aNewState == AudioContextState::Running) ||
-        (mAudioContextState == AudioContextState::Running &&
-         aNewState == AudioContextState::Suspended) ||
-        (mAudioContextState == AudioContextState::Running &&
-         aNewState == AudioContextState::Closed) ||
-        (mAudioContextState == AudioContextState::Suspended &&
-         aNewState == AudioContextState::Closed) ||
-        (mAudioContextState == aNewState))) {
+  if (mAudioContextState == AudioContextState::Closed) {
     fprintf(stderr,
             "Invalid transition: mAudioContextState: %d -> aNewState %d\n",
             static_cast<int>(mAudioContextState), static_cast<int>(aNewState));
     MOZ_ASSERT(false);
   }
 
-#    endif  // DEBUG
-#  endif    // XP_MACOSX
-#endif      // WIN32
-
   if (aPromise) {
     Promise* promise = reinterpret_cast<Promise*>(aPromise);
     // It is possible for the promise to have been removed from
@@ -1181,7 +1149,7 @@ void AudioContext::CloseInternal(void* aPromise,
            aPromise](AudioContextState aNewState) {
             self->OnStateChanged(aPromise, aNewState);
           },
-          [] { MOZ_CRASH("Unexpected rejection"); });
+          [] {});  // Promise may be rejected after graph shutdown.
     }
   }
   mCloseCalled = true;