Backed out 2 changesets (bug 1709184) for xpcshell failures. CLOSED TREE

Backed out changeset 46d7864a45df (bug 1709184)
Backed out changeset ac48b4d61b39 (bug 1709184)

xpcom/base/AppShutdown.cpp

@@ -315,7 +315,6 @@ bool AppShutdown::IsRestarting() {
 
 #ifdef DEBUG
 static bool sNotifyingShutdownObservers = false;
-static bool sAdvancingShutdownPhase = false;
 
 bool AppShutdown::IsNoOrLegalShutdownTopic(const char* aTopic) {
   if (!XRE_IsParentProcess()) {
@@ -333,12 +332,6 @@ void AppShutdown::AdvanceShutdownPhaseInternal(
     ShutdownPhase aPhase, bool doNotify, const char16_t* aNotificationData,
     const nsCOMPtr<nsISupports>& aNotificationSubject) {
   AssertIsOnMainThread();
-#ifdef DEBUG
-  // Prevent us from re-entrance
-  MOZ_ASSERT(!sAdvancingShutdownPhase);
-  sAdvancingShutdownPhase = true;
-  auto exit = MakeScopeExit([] { sAdvancingShutdownPhase = false; });
-#endif
 
   // We ensure that we can move only forward. We cannot
   // MOZ_ASSERT here as there are some tests that fire
@@ -347,23 +340,6 @@ void AppShutdown::AdvanceShutdownPhaseInternal(
   if (sCurrentShutdownPhase >= aPhase) {
     return;
   }
-
-  nsCOMPtr<nsIThread> thread = do_GetCurrentThread();
-  if (sCurrentShutdownPhase >= ShutdownPhase::AppShutdownConfirmed) {
-    // Give runnables dispatched so far as part of the ongoing phase a chance
-    // to run before actually advancing the phase. We can do this only after
-    // we passed the point of no return and thus can expect a linear flow
-    // through our shutdown phases. This way the processing is also covered
-    // by the terminator's timer.
-    // Note that this happens only for main thread runnables, such that the
-    // correct way of ensuring shutdown processing remains to have an async
-    // shutdown blocker.
-    if (thread) {
-      NS_ProcessPendingEvents(thread);
-    }
-  }
-
-  // From now on any IsInOrBeyond checks will find the new phase set.
   sCurrentShutdownPhase = aPhase;
 
   // TODO: Bug 1768581
@@ -395,10 +371,6 @@ void AppShutdown::AdvanceShutdownPhaseInternal(
 #endif
         obsService->NotifyObservers(aNotificationSubject, aTopic,
                                     aNotificationData);
-        // Empty our MT event queue again after the notification has finished
-        if (thread) {
-          NS_ProcessPendingEvents(thread);
-        }
       }
     }
   }

xpcom/build/XPCOMInit.cpp

@@ -585,6 +585,7 @@ nsresult ShutdownXPCOM(nsIServiceManager* aServMgr) {
 
     // This must happen after the shutdown of media and widgets, which
     // are triggered by the NS_XPCOM_SHUTDOWN_OBSERVER_ID notification.
+    NS_ProcessPendingEvents(thread);
     gfxPlatform::ShutdownLayersIPC();
 
     mozilla::AppShutdown::AdvanceShutdownPhase(
@@ -594,11 +595,11 @@ nsresult ShutdownXPCOM(nsIServiceManager* aServMgr) {
     // dispatches to non main-thread threads.
     ThreadEventTarget::XPCOMShutdownThreadsNotificationFinished();
 #endif
+    NS_ProcessPendingEvents(thread);
 
     // Shutdown the timer thread and all timers that might still be alive
     nsTimerImpl::Shutdown();
 
-    // Have an extra round of processing after the timers went away.
     NS_ProcessPendingEvents(thread);
 
     // Shutdown all remaining threads.  This method does not return until
@@ -616,9 +617,11 @@ nsresult ShutdownXPCOM(nsIServiceManager* aServMgr) {
     // XPCOMShutdownFinal is the default phase for ClearOnShutdown.
     // This AdvanceShutdownPhase will thus free most ClearOnShutdown()'ed
     // smart pointers. Some destructors may fire extra main thread runnables
-    // that will be processed inside AdvanceShutdownPhase.
+    // that will be processed below.
     AppShutdown::AdvanceShutdownPhase(ShutdownPhase::XPCOMShutdownFinal);
 
+    NS_ProcessPendingEvents(thread);
+
     // Shutdown the main thread, processing our last round of events, and then
     // mark that we've finished main thread event processing.
     nsThreadManager::get().ShutdownMainThread();