Add constructor that takes only a Context

#minor-release

PiperOrigin-RevId: 604659845
(cherry picked from commit c2273345c5)

RELEASENOTES.md

@@ -22,6 +22,8 @@
 *   Session:
     *   Fix issue where `MediaItem.RequestMetadata` with just non-null extras is
         not sent transmitted between media controllers and sessions.
+    *   Add constructor to `MediaLibrarySession.Builder` that only takes a
+        `Context` instead of a `MediaLibraryService`.
 *   UI:
 *   Downloads:
 *   OkHttp Extension:

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

@@ -413,6 +413,19 @@ public abstract class MediaLibraryService extends MediaSessionService {
         super(service, player, callback);
       }
 
+      /**
+       * Creates a builder for {@link MediaLibrarySession}.
+       *
+       * @param context The {@link Context}.
+       * @param player The underlying player to perform playback and handle transport controls.
+       * @param callback The callback to handle requests from {@link MediaBrowser}.
+       * @throws IllegalArgumentException if {@link Player#canAdvertiseSession()} returns false.
+       */
+      @UnstableApi
+      public Builder(Context context, Player player, Callback callback) {
+        super(context, player, callback);
+      }
+
       /**
        * Sets a {@link PendingIntent} to launch an {@link android.app.Activity} for the {@link
        * MediaLibrarySession}. This can be used as a quick link to an ongoing media screen.