--- a/hal/Hal.cpp
+++ b/hal/Hal.cpp
@@ -349,17 +349,23 @@ protected:
     PROXY_IF_SANDBOXED(DisableScreenConfigurationNotifications());
   }
 
   void GetCurrentInformationInternal(ScreenConfiguration* aInfo) {
     PROXY_IF_SANDBOXED(GetCurrentScreenConfiguration(aInfo));
   }
 };
 
-static ScreenConfigurationObserversManager sScreenConfigurationObservers;
+static ScreenConfigurationObserversManager&
+ScreenConfigurationObservers()
+{
+  AssertMainThread();
+  static ScreenConfigurationObserversManager sScreenConfigurationObservers;
+  return sScreenConfigurationObservers;
+}
 
 void
 RegisterBatteryObserver(BatteryObserver* aObserver)
 {
   AssertMainThread();
   BatteryObservers().AddObserver(aObserver);
 }
 
@@ -697,38 +703,38 @@ NotifyWakeLockChange(const WakeLockInfor
   AssertMainThread();
   sWakeLockObservers.BroadcastInformation(aInfo);
 }
 
 void
 RegisterScreenConfigurationObserver(ScreenConfigurationObserver* aObserver)
 {
   AssertMainThread();
-  sScreenConfigurationObservers.AddObserver(aObserver);
+  ScreenConfigurationObservers().AddObserver(aObserver);
 }
 
 void
 UnregisterScreenConfigurationObserver(ScreenConfigurationObserver* aObserver)
 {
   AssertMainThread();
-  sScreenConfigurationObservers.RemoveObserver(aObserver);
+  ScreenConfigurationObservers().RemoveObserver(aObserver);
 }
 
 void
 GetCurrentScreenConfiguration(ScreenConfiguration* aScreenConfiguration)
 {
   AssertMainThread();
-  *aScreenConfiguration = sScreenConfigurationObservers.GetCurrentInformation();
+  *aScreenConfiguration = ScreenConfigurationObservers().GetCurrentInformation();
 }
 
 void
 NotifyScreenConfigurationChange(const ScreenConfiguration& aScreenConfiguration)
 {
-  sScreenConfigurationObservers.CacheInformation(aScreenConfiguration);
-  sScreenConfigurationObservers.BroadcastCachedInformation();
+  ScreenConfigurationObservers().CacheInformation(aScreenConfiguration);
+  ScreenConfigurationObservers().BroadcastCachedInformation();
 }
 
 bool
 LockScreenOrientation(const dom::ScreenOrientationInternal& aOrientation)
 {
   AssertMainThread();
   RETURN_PROXY_IF_SANDBOXED(LockScreenOrientation(aOrientation), false);
 }