Avoid using ConcurrentHashMap

Use Collections.synchronizedSet() instead of creating a set from a
ConcurrentHashMap because ConcurrentHashMap has a bug in APIs 21/22
that can result in lost updates.

PiperOrigin-RevId: 453696565
(cherry picked from commit d506c709)

libraries/session/src/main/java/androidx/media3/session/MediaSessionService.java

@@ -43,10 +43,10 @@ import androidx.media3.session.MediaSession.ControllerInfo;
 import java.lang.ref.WeakReference;
 import java.util.ArrayList;
 import java.util.Collections;
+import java.util.HashSet;
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
-import java.util.concurrent.ConcurrentHashMap;
 import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
 
 /**
@@ -472,7 +472,8 @@ public abstract class MediaSessionService extends Service {
       Context context = serviceReference.getApplicationContext();
       handler = new Handler(context.getMainLooper());
       mediaSessionManager = MediaSessionManager.getSessionManager(context);
-      pendingControllers = Collections.newSetFromMap(new ConcurrentHashMap<>());
+      // ConcurrentHashMap has a bug in APIs 21-22 that can result in lost updates.
+      pendingControllers = Collections.synchronizedSet(new HashSet<>());
     }
 
     @Override

libraries/session/src/main/java/androidx/media3/session/MediaSessionStub.java

@@ -83,10 +83,10 @@ import com.google.common.util.concurrent.MoreExecutors;
 import java.lang.ref.WeakReference;
 import java.util.Collections;
 import java.util.Deque;
+import java.util.HashSet;
 import java.util.List;
 import java.util.Set;
 import java.util.concurrent.CancellationException;
-import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.ExecutionException;
 
 /**
@@ -109,7 +109,8 @@ import java.util.concurrent.ExecutionException;
     this.sessionImpl = new WeakReference<>(sessionImpl);
     sessionManager = MediaSessionManager.getSessionManager(sessionImpl.getContext());
     connectedControllersManager = new ConnectedControllersManager<>(sessionImpl);
-    pendingControllers = Collections.newSetFromMap(new ConcurrentHashMap<>());
+    // ConcurrentHashMap has a bug in APIs 21-22 that can result in lost updates.
+    pendingControllers = Collections.synchronizedSet(new HashSet<>());
   }
 
   public ConnectedControllersManager<IBinder> getConnectedControllersManager() {