Fixing bug 516113. Don't let new windows open up after we've started XPCOM shutdown. r=bsmedberg, a=blocking1.9.2+

xpcom/build/nsXPCOM.h

@@ -520,6 +520,13 @@ NS_CycleCollectorForget2(nsPurpleBufferEntry *e);
  */
 #define NS_XPCOM_STARTUP_OBSERVER_ID "xpcom-startup"
 
+/**
+ * At XPCOM shutdown, this topic is notified just before "xpcom-shutdown".
+ * Components should only use this to mark themselves as 'being destroyed'.
+ * Nothing should be dispatched to any event loop.
+ */
+#define NS_XPCOM_WILL_SHUTDOWN_OBSERVER_ID "xpcom-will-shutdown"
+
 /**
  * At XPCOM shutdown, this topic is notified. All components must
  * release any interface references to objects in other modules when

xpcom/build/nsXPComInit.cpp

@@ -679,6 +679,10 @@ ShutdownXPCOM(nsIServiceManager* servMgr)
 
         if (observerService)
         {
+            (void) observerService->
+                NotifyObservers(nsnull, NS_XPCOM_WILL_SHUTDOWN_OBSERVER_ID,
+                                nsnull);
+
             nsCOMPtr<nsIServiceManager> mgr;
             rv = NS_GetServiceManager(getter_AddRefs(mgr));
             if (NS_SUCCEEDED(rv))

xpfe/appshell/src/nsAppShellService.cpp

@@ -82,6 +82,7 @@
 class nsIAppShell;
 
 nsAppShellService::nsAppShellService() : 
+  mXPCOMWillShutDown(PR_FALSE),
   mXPCOMShuttingDown(PR_FALSE),
   mModalWindowCount(0),
   mApplicationProvidedHiddenWindow(PR_FALSE)
@@ -89,8 +90,10 @@ nsAppShellService::nsAppShellService() :
   nsCOMPtr<nsIObserverService> obs
     (do_GetService("@mozilla.org/observer-service;1"));
 
-  if (obs)
+  if (obs) {
+    obs->AddObserver(this, "xpcom-will-shutdown", PR_FALSE);
     obs->AddObserver(this, "xpcom-shutdown", PR_FALSE);
+  }
 }
 
 nsAppShellService::~nsAppShellService()
@@ -297,6 +300,7 @@ nsAppShellService::JustCreateTopWindow(nsIXULWindow *aParent,
                                        nsWebShellWindow **aResult)
 {
   *aResult = nsnull;
+  NS_ENSURE_STATE(!mXPCOMWillShutDown);
 
   nsCOMPtr<nsIXULWindow> parent;
   if (aChromeMask & nsIWebBrowserChrome::CHROME_DEPENDENT)
@@ -562,12 +566,16 @@ NS_IMETHODIMP
 nsAppShellService::Observe(nsISupports* aSubject, const char *aTopic,
                            const PRUnichar *aData)
 {
-  NS_ASSERTION(!strcmp(aTopic, "xpcom-shutdown"), "Unexpected observer topic!");
-
-  mXPCOMShuttingDown = PR_TRUE;
-  if (mHiddenWindow) {
-    ClearXPConnectSafeContext();
-    mHiddenWindow->Destroy();
+  if (!strcmp(aTopic, "xpcom-will-shutdown")) {
+    mXPCOMWillShutDown = PR_TRUE;
+  } else if (!strcmp(aTopic, "xpcom-shutdown")) {
+    mXPCOMShuttingDown = PR_TRUE;
+    if (mHiddenWindow) {
+      ClearXPConnectSafeContext();
+      mHiddenWindow->Destroy();
+    }
+  } else {
+    NS_ERROR("Unexpected observer topic!");
   }
 
   return NS_OK;

xpfe/appshell/src/nsAppShellService.h

@@ -74,6 +74,7 @@ protected:
   nsresult ClearXPConnectSafeContext();
 
   nsRefPtr<nsWebShellWindow>  mHiddenWindow;
+  PRPackedBool                mXPCOMWillShutDown;
   PRPackedBool                mXPCOMShuttingDown;
   PRUint16                    mModalWindowCount;
   PRPackedBool                mApplicationProvidedHiddenWindow;