Reshuffle the way listeners are attached to MediaSources

This better supports custom listener types defined by MediaSource
subclasses.

Part of issue:#6765

PiperOrigin-RevId: 308050575

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

@@ -22,6 +22,7 @@ import com.google.android.exoplayer2.Timeline;
 import com.google.android.exoplayer2.drm.DrmSessionEventListener;
 import com.google.android.exoplayer2.upstream.TransferListener;
 import com.google.android.exoplayer2.util.Assertions;
+import com.google.android.exoplayer2.util.MediaSourceEventDispatcher;
 import java.util.ArrayList;
 import java.util.HashSet;
 
@@ -133,22 +134,44 @@ public abstract class BaseMediaSource implements MediaSource {
 
   @Override
   public final void addEventListener(Handler handler, MediaSourceEventListener eventListener) {
-    eventDispatcher.addEventListener(handler, eventListener);
+    addEventListenerInternal(handler, eventListener, MediaSourceEventListener.class);
   }
 
   @Override
   public final void removeEventListener(MediaSourceEventListener eventListener) {
-    eventDispatcher.removeEventListener(eventListener);
+    removeEventListenerInternal(eventListener, MediaSourceEventListener.class);
   }
 
   @Override
   public final void addDrmEventListener(Handler handler, DrmSessionEventListener eventListener) {
-    eventDispatcher.addEventListener(handler, eventListener, DrmSessionEventListener.class);
+    addEventListenerInternal(handler, eventListener, DrmSessionEventListener.class);
   }
 
   @Override
   public final void removeDrmEventListener(DrmSessionEventListener eventListener) {
-    eventDispatcher.removeEventListener(eventListener, DrmSessionEventListener.class);
+    removeEventListenerInternal(eventListener, DrmSessionEventListener.class);
+  }
+
+  /**
+   * Adds a listener to the internal {@link MediaSourceEventDispatcher} with the provided type.
+   *
+   * <p>NOTE: Read the caveats on {@link MediaSourceEventDispatcher#addEventListener(Handler,
+   * Object, Class)} when deciding what value to pass for {@code listenerClass}.
+   *
+   * @see MediaSourceEventDispatcher#addEventListener(Handler, Object, Class)
+   */
+  protected final <T> void addEventListenerInternal(
+      Handler handler, T eventListener, Class<T> listenerClass) {
+    eventDispatcher.addEventListener(handler, eventListener, listenerClass);
+  }
+
+  /**
+   * Removes a listener from the internal {@link MediaSourceEventDispatcher}.
+   *
+   * @see MediaSourceEventDispatcher#removeEventListener(Object, Class)
+   */
+  protected final <T> void removeEventListenerInternal(T eventListener, Class<T> listenerClass) {
+    eventDispatcher.removeEventListener(eventListener, listenerClass);
   }
 
   @Override

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

@@ -16,7 +16,6 @@
 package com.google.android.exoplayer2.source;
 
 import android.net.Uri;
-import android.os.Handler;
 import androidx.annotation.Nullable;
 import com.google.android.exoplayer2.C;
 import com.google.android.exoplayer2.Format;
@@ -188,33 +187,6 @@ public interface MediaSourceEventListener {
       return new EventDispatcher(listenerInfos, windowIndex, mediaPeriodId, mediaTimeOffsetMs);
     }
 
-    /**
-     * Adds a {@link MediaSourceEventListener} to the event dispatcher.
-     *
-     * <p>This is equivalent to {@link #addEventListener(Handler, Object, Class)} with {@code
-     * listenerClass = MediaSourceEventListener.class} and is intended to ease the transition to
-     * using {@link MediaSourceEventDispatcher} everywhere.
-     *
-     * @param handler A handler on the which listener events will be posted.
-     * @param eventListener The listener to be added.
-     */
-    public void addEventListener(Handler handler, MediaSourceEventListener eventListener) {
-      addEventListener(handler, eventListener, MediaSourceEventListener.class);
-    }
-
-    /**
-     * Removes a {@link MediaSourceEventListener} from the event dispatcher.
-     *
-     * <p>This is equivalent to {@link #removeEventListener(Object, Class)} with {@code
-     * listenerClass = MediaSourceEventListener.class} and is intended to ease the transition to
-     * using {@link MediaSourceEventDispatcher} everywhere.
-     *
-     * @param eventListener The listener to be removed.
-     */
-    public void removeEventListener(MediaSourceEventListener eventListener) {
-      removeEventListener(eventListener, MediaSourceEventListener.class);
-    }
-
     public void mediaPeriodCreated() {
       dispatch(
           (listener, windowIndex, mediaPeriodId) ->