Explicitly declare IdentityHashMap types

PiperOrigin-RevId: 319520755

library/core/src/main/java/com/google/android/exoplayer2/MediaSourceList.java

@@ -67,7 +67,7 @@ import java.util.Set;
   private static final String TAG = "MediaSourceList";
 
   private final List<MediaSourceHolder> mediaSourceHolders;
-  private final Map<MediaPeriod, MediaSourceHolder> mediaSourceByMediaPeriod;
+  private final IdentityHashMap<MediaPeriod, MediaSourceHolder> mediaSourceByMediaPeriod;
   private final Map<Object, MediaSourceHolder> mediaSourceByUid;
   private final MediaSourceListInfoRefreshListener mediaSourceListInfoListener;
   private final MediaSourceEventListener.EventDispatcher eventDispatcher;

library/core/src/main/java/com/google/android/exoplayer2/source/ConcatenatingMediaSource.java

@@ -72,7 +72,7 @@ public final class ConcatenatingMediaSource extends CompositeMediaSource<MediaSo
 
   // Accessed on the playback thread only.
   private final List<MediaSourceHolder> mediaSourceHolders;
-  private final Map<MediaPeriod, MediaSourceHolder> mediaSourceByMediaPeriod;
+  private final IdentityHashMap<MediaPeriod, MediaSourceHolder> mediaSourceByMediaPeriod;
   private final Map<Object, MediaSourceHolder> mediaSourceByUid;
   private final Set<MediaSourceHolder> enabledMediaSourceHolders;
   private final boolean isAtomic;