--- a/dom/camera/CameraPreviewMediaStream.cpp
+++ b/dom/camera/CameraPreviewMediaStream.cpp
@@ -12,19 +12,19 @@
  * either very busy or the device is busy elsewhere (e.g. encoding or
  * persisting video data).
  */
 #define MAX_INVALIDATE_PENDING 4
 
 using namespace mozilla::layers;
 using namespace mozilla::dom;
 
-static const TrackID TRACK_VIDEO = 2;
+namespace mozilla {
 
-namespace mozilla {
+static const TrackID TRACK_VIDEO = 2;
 
 void
 FakeMediaStreamGraph::DispatchToMainThreadAfterStreamStateUpdate(already_AddRefed<nsIRunnable> aRunnable)
 {
   nsRefPtr<nsIRunnable> task = aRunnable;
   NS_DispatchToMainThread(task);
 }