Fixed a bug where the media entries are invisible after switching users

Because the list was only cleared after notifying the listeners,
their checks if we still have active players was using an old
state.

Bug: 158367094
Test: add media, switch users
Change-Id: I524cadfd02967e7bd017ebf4cee2beb5bfaef26d

packages/SystemUI/src/com/android/systemui/media/MediaDataManager.kt

@@ -193,12 +193,15 @@ class MediaDataManager(
     private fun clearData() {
         // Called on user change. Remove all current MediaData objects and inform listeners
         val listenersCopy = listeners.toSet()
-        mediaEntries.forEach {
+        val keyCopy = mediaEntries.keys.toMutableList()
+        // Clear the list first, to make sure callbacks from listeners if we have any entries
+        // are up to date
+        mediaEntries.clear()
+        keyCopy.forEach {
             listenersCopy.forEach { listener ->
-                listener.onMediaDataRemoved(it.key)
+                listener.onMediaDataRemoved(it)
             }
         }
-        mediaEntries.clear()
     }
 
     private fun removeAllForPackage(packageName: String) {