Bug 1558103 - Don't try to dispatch XPCOM events during shutdown. r=aklotz

XPCOM complains when events are dispatched during shutdown. Since we're
shutting down, there's no really any point in dispatching these messages
anyway, so we can safely ignore them.

Differential Revision: https://phabricator.services.mozilla.com/D113203

widget/android/nsAppShell.cpp

@@ -25,6 +25,7 @@
 #include "mozilla/dom/GeolocationPosition.h"
 
 #include "mozilla/ArrayUtils.h"
+#include "mozilla/AppShutdown.h"
 #include "mozilla/Components.h"
 #include "mozilla/Services.h"
 #include "mozilla/Preferences.h"
@@ -342,6 +343,11 @@ class XPCOMEventTargetWrapper final
  public:
   // Wraps a java runnable into an XPCOM runnable and dispatches it to mTarget.
   void DispatchNative(mozilla::jni::Object::Param aJavaRunnable) {
+    if (AppShutdown::GetCurrentShutdownPhase() >=
+        ShutdownPhase::XPCOMShutdownThreads) {
+      // No point in trying to dispatch this if we're already shutting down.
+      return;
+    }
     java::XPCOMEventTarget::JNIRunnable::GlobalRef r =
         java::XPCOMEventTarget::JNIRunnable::Ref::From(aJavaRunnable);
     mTarget->Dispatch(NS_NewRunnableFunction(