Allow multiple media source event listeners.

This is achieved by moving the listener registration and the creation of the
event dispatcher into BaseMediaSource.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=188461932

RELEASENOTES.md

@@ -31,6 +31,8 @@
     date time is still available via the informational
     `Timeline.Window.windowStartTimeMs` field
     ([#3865](https://github.com/google/ExoPlayer/issues/3865)).
+  * Allow adding and removing `MediaSourceEventListener`s to MediaSources after
+    they have been created.
 * Enable seeking in MP4 streams where duration is set incorrectly in the track
   header ([#3926](https://github.com/google/ExoPlayer/issues/3926)).
 * Video: force rendering a frame periodically in `MediaCodecVideoRenderer` and

demos/ima/src/main/java/com/google/android/exoplayer2/imademo/PlayerManager.java

@@ -17,8 +17,6 @@ package com.google.android.exoplayer2.imademo;
 
 import android.content.Context;
 import android.net.Uri;
-import android.os.Handler;
-import android.support.annotation.Nullable;
 import com.google.android.exoplayer2.C;
 import com.google.android.exoplayer2.C.ContentType;
 import com.google.android.exoplayer2.ExoPlayer;
@@ -27,7 +25,6 @@ import com.google.android.exoplayer2.SimpleExoPlayer;
 import com.google.android.exoplayer2.ext.ima.ImaAdsLoader;
 import com.google.android.exoplayer2.source.ExtractorMediaSource;
 import com.google.android.exoplayer2.source.MediaSource;
-import com.google.android.exoplayer2.source.MediaSourceEventListener;
 import com.google.android.exoplayer2.source.ads.AdsMediaSource;
 import com.google.android.exoplayer2.source.dash.DashMediaSource;
 import com.google.android.exoplayer2.source.dash.DefaultDashChunkSource;
@@ -83,8 +80,7 @@ import com.google.android.exoplayer2.util.Util;
 
     // This is the MediaSource representing the content media (i.e. not the ad).
     String contentUrl = context.getString(R.string.content_url);
-    MediaSource contentMediaSource =
-        buildMediaSource(Uri.parse(contentUrl), /* handler= */ null, /* listener= */ null);
+    MediaSource contentMediaSource = buildMediaSource(Uri.parse(contentUrl));
 
     // Compose the content media source into a new AdsMediaSource with both ads and content.
     MediaSource mediaSourceWithAds =
@@ -121,9 +117,8 @@ import com.google.android.exoplayer2.util.Util;
   // AdsMediaSource.MediaSourceFactory implementation.
 
   @Override
-  public MediaSource createMediaSource(
-      Uri uri, @Nullable Handler handler, @Nullable MediaSourceEventListener listener) {
-    return buildMediaSource(uri, handler, listener);
+  public MediaSource createMediaSource(Uri uri) {
+    return buildMediaSource(uri);
   }
 
   @Override
@@ -134,25 +129,22 @@ import com.google.android.exoplayer2.util.Util;
 
   // Internal methods.
 
-  private MediaSource buildMediaSource(
-      Uri uri, @Nullable Handler handler, @Nullable MediaSourceEventListener listener) {
+  private MediaSource buildMediaSource(Uri uri) {
     @ContentType int type = Util.inferContentType(uri);
     switch (type) {
       case C.TYPE_DASH:
         return new DashMediaSource.Factory(
                 new DefaultDashChunkSource.Factory(mediaDataSourceFactory),
                 manifestDataSourceFactory)
-            .createMediaSource(uri, handler, listener);
+            .createMediaSource(uri);
       case C.TYPE_SS:
         return new SsMediaSource.Factory(
                 new DefaultSsChunkSource.Factory(mediaDataSourceFactory), manifestDataSourceFactory)
-            .createMediaSource(uri, handler, listener);
+            .createMediaSource(uri);
       case C.TYPE_HLS:
-        return new HlsMediaSource.Factory(mediaDataSourceFactory)
-            .createMediaSource(uri, handler, listener);
+        return new HlsMediaSource.Factory(mediaDataSourceFactory).createMediaSource(uri);
       case C.TYPE_OTHER:
-        return new ExtractorMediaSource.Factory(mediaDataSourceFactory)
-            .createMediaSource(uri, handler, listener);
+        return new ExtractorMediaSource.Factory(mediaDataSourceFactory).createMediaSource(uri);
       default:
         throw new IllegalStateException("Unsupported type: " + type);
     }

demos/main/src/main/java/com/google/android/exoplayer2/demo/PlayerActivity.java

@@ -53,7 +53,6 @@ import com.google.android.exoplayer2.source.BehindLiveWindowException;
 import com.google.android.exoplayer2.source.ConcatenatingMediaSource;
 import com.google.android.exoplayer2.source.ExtractorMediaSource;
 import com.google.android.exoplayer2.source.MediaSource;
-import com.google.android.exoplayer2.source.MediaSourceEventListener;
 import com.google.android.exoplayer2.source.TrackGroupArray;
 import com.google.android.exoplayer2.source.ads.AdsLoader;
 import com.google.android.exoplayer2.source.ads.AdsMediaSource;
@@ -342,7 +341,8 @@ public class PlayerActivity extends Activity
       }
       MediaSource[] mediaSources = new MediaSource[uris.length];
       for (int i = 0; i < uris.length; i++) {
-        mediaSources[i] = buildMediaSource(uris[i], extensions[i], mainHandler, eventLogger);
+        mediaSources[i] = buildMediaSource(uris[i], extensions[i]);
+        mediaSources[i].addEventListener(mainHandler, eventLogger);
       }
       mediaSource =
           mediaSources.length == 1 ? mediaSources[0] : new ConcatenatingMediaSource(mediaSources);
@@ -372,11 +372,7 @@ public class PlayerActivity extends Activity
     updateButtonVisibilities();
   }
 
-  private MediaSource buildMediaSource(
-      Uri uri,
-      String overrideExtension,
-      @Nullable Handler handler,
-      @Nullable MediaSourceEventListener listener) {
+  private MediaSource buildMediaSource(Uri uri, String overrideExtension) {
     @ContentType int type = TextUtils.isEmpty(overrideExtension) ? Util.inferContentType(uri)
         : Util.inferContentType("." + overrideExtension);
     switch (type) {
@@ -384,18 +380,16 @@ public class PlayerActivity extends Activity
         return new DashMediaSource.Factory(
                 new DefaultDashChunkSource.Factory(mediaDataSourceFactory),
                 buildDataSourceFactory(false))
-            .createMediaSource(uri, handler, listener);
+            .createMediaSource(uri);
       case C.TYPE_SS:
         return new SsMediaSource.Factory(
                 new DefaultSsChunkSource.Factory(mediaDataSourceFactory),
                 buildDataSourceFactory(false))
-            .createMediaSource(uri, handler, listener);
+            .createMediaSource(uri);
       case C.TYPE_HLS:
-        return new HlsMediaSource.Factory(mediaDataSourceFactory)
-            .createMediaSource(uri, handler, listener);
+        return new HlsMediaSource.Factory(mediaDataSourceFactory).createMediaSource(uri);
       case C.TYPE_OTHER:
-        return new ExtractorMediaSource.Factory(mediaDataSourceFactory)
-            .createMediaSource(uri, handler, listener);
+        return new ExtractorMediaSource.Factory(mediaDataSourceFactory).createMediaSource(uri);
       default: {
         throw new IllegalStateException("Unsupported type: " + type);
       }
@@ -488,10 +482,8 @@ public class PlayerActivity extends Activity
       AdsMediaSource.MediaSourceFactory adMediaSourceFactory =
           new AdsMediaSource.MediaSourceFactory() {
             @Override
-            public MediaSource createMediaSource(
-                Uri uri, @Nullable Handler handler, @Nullable MediaSourceEventListener listener) {
-              return PlayerActivity.this.buildMediaSource(
-                  uri, /* overrideExtension= */ null, handler, listener);
+            public MediaSource createMediaSource(Uri uri) {
+              return PlayerActivity.this.buildMediaSource(uri, /* overrideExtension= */ null);
             }
 
             @Override

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

@@ -15,6 +15,7 @@
  */
 package com.google.android.exoplayer2.source;
 
+import android.os.Handler;
 import android.support.annotation.Nullable;
 import com.google.android.exoplayer2.ExoPlayer;
 import com.google.android.exoplayer2.Timeline;
@@ -22,7 +23,8 @@ import com.google.android.exoplayer2.util.Assertions;
 import java.util.ArrayList;
 
 /**
- * Base {@link MediaSource} implementation to handle parallel reuse.
+ * Base {@link MediaSource} implementation to handle parallel reuse and to keep a list of {@link
+ * MediaSourceEventListener}s.
  *
  * <p>Whenever an implementing subclass needs to provide a new timeline and/or manifest, it must
  * call {@link #refreshSourceInfo(Timeline, Object)} to notify all listeners.
@@ -30,6 +32,7 @@ import java.util.ArrayList;
 public abstract class BaseMediaSource implements MediaSource {
 
   private final ArrayList<SourceInfoRefreshListener> sourceInfoListeners;
+  private final MediaSourceEventListener.EventDispatcher eventDispatcher;
 
   private ExoPlayer player;
   private Timeline timeline;
@@ -37,6 +40,7 @@ public abstract class BaseMediaSource implements MediaSource {
 
   public BaseMediaSource() {
     sourceInfoListeners = new ArrayList<>(/* initialCapacity= */ 1);
+    eventDispatcher = new MediaSourceEventListener.EventDispatcher();
   }
 
   /**
@@ -70,6 +74,24 @@ public abstract class BaseMediaSource implements MediaSource {
     }
   }
 
+  /**
+   * Returns a {@link MediaSourceEventListener.EventDispatcher} which dispatches all events to the
+   * registered listeners.
+   */
+  protected final MediaSourceEventListener.EventDispatcher getEventDispatcher() {
+    return eventDispatcher;
+  }
+
+  @Override
+  public final void addEventListener(Handler handler, MediaSourceEventListener eventListener) {
+    eventDispatcher.addEventListener(handler, eventListener);
+  }
+
+  @Override
+  public final void removeEventListener(MediaSourceEventListener eventListener) {
+    eventDispatcher.removeEventListener(eventListener);
+  }
+
   @Override
   public final void prepareSource(
       ExoPlayer player, boolean isTopLevelSource, SourceInfoRefreshListener listener) {

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

@@ -187,34 +187,38 @@ public final class ExtractorMediaSource extends BaseMediaSource
     }
 
     /**
-     * Returns a new {@link ExtractorMediaSource} using the current parameters. Media source events
-     * will not be delivered.
+     * Returns a new {@link ExtractorMediaSource} using the current parameters.
      *
      * @param uri The {@link Uri}.
      * @return The new {@link ExtractorMediaSource}.
      */
+    @Override
     public ExtractorMediaSource createMediaSource(Uri uri) {
-      return createMediaSource(uri, null, null);
+      isCreateCalled = true;
+      if (extractorsFactory == null) {
+        extractorsFactory = new DefaultExtractorsFactory();
+      }
+      return new ExtractorMediaSource(
+          uri,
+          dataSourceFactory,
+          extractorsFactory,
+          minLoadableRetryCount,
+          customCacheKey,
+          continueLoadingCheckIntervalBytes);
     }
 
     /**
-     * Returns a new {@link ExtractorMediaSource} using the current parameters.
-     *
-     * @param uri The {@link Uri}.
-     * @param eventHandler A handler for events.
-     * @param eventListener A listener of events.
-     * @return The new {@link ExtractorMediaSource}.
+     * @deprecated Use {@link #createMediaSource(Uri)} and {@link #addEventListener(Handler,
+     *     MediaSourceEventListener)} instead.
      */
-    @Override
+    @Deprecated
     public ExtractorMediaSource createMediaSource(
         Uri uri, @Nullable Handler eventHandler, @Nullable MediaSourceEventListener eventListener) {
-      isCreateCalled = true;
-      if (extractorsFactory == null) {
-        extractorsFactory = new DefaultExtractorsFactory();
+      ExtractorMediaSource mediaSource = createMediaSource(uri);
+      if (eventHandler != null && eventListener != null) {
+        mediaSource.addEventListener(eventHandler, eventListener);
       }
-      return new ExtractorMediaSource(uri, dataSourceFactory, extractorsFactory,
-          minLoadableRetryCount, eventHandler, eventListener, customCacheKey,
-          continueLoadingCheckIntervalBytes);
+      return mediaSource;
     }
 
     @Override
@@ -297,10 +301,11 @@ public final class ExtractorMediaSource extends BaseMediaSource
         dataSourceFactory,
         extractorsFactory,
         minLoadableRetryCount,
-        eventHandler,
-        eventListener == null ? null : new EventListenerWrapper(eventListener),
         customCacheKey,
         continueLoadingCheckIntervalBytes);
+    if (eventListener != null && eventHandler != null) {
+      addEventListener(eventHandler, new EventListenerWrapper(eventListener));
+    }
   }
 
   private ExtractorMediaSource(
@@ -308,15 +313,13 @@ public final class ExtractorMediaSource extends BaseMediaSource
       DataSource.Factory dataSourceFactory,
       ExtractorsFactory extractorsFactory,
       int minLoadableRetryCount,
-      @Nullable Handler eventHandler,
-      @Nullable MediaSourceEventListener eventListener,
       @Nullable String customCacheKey,
       int continueLoadingCheckIntervalBytes) {
     this.uri = uri;
     this.dataSourceFactory = dataSourceFactory;
     this.extractorsFactory = extractorsFactory;
     this.minLoadableRetryCount = minLoadableRetryCount;
-    this.eventDispatcher = new EventDispatcher(eventHandler, eventListener);
+    this.eventDispatcher = getEventDispatcher();
     this.customCacheKey = customCacheKey;
     this.continueLoadingCheckIntervalBytes = continueLoadingCheckIntervalBytes;
     this.timelineDurationUs = C.TIME_UNSET;

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

@@ -15,6 +15,7 @@
  */
 package com.google.android.exoplayer2.source;
 
+import android.os.Handler;
 import android.support.annotation.Nullable;
 import com.google.android.exoplayer2.C;
 import com.google.android.exoplayer2.ExoPlayer;
@@ -172,6 +173,23 @@ public interface MediaSource {
   }
 
   /**
+   * Adds a {@link MediaSourceEventListener} to the list of listeners which are notified of media
+   * source events.
+   *
+   * @param handler A handler on the which listener events will be posted.
+   * @param eventListener The listener to be added.
+   */
+  void addEventListener(Handler handler, MediaSourceEventListener eventListener);
+
+  /**
+   * Removes a {@link MediaSourceEventListener} from the list of listeners which are notified of
+   * media source events.
+   *
+   * @param eventListener The listener to be removed.
+   */
+  void removeEventListener(MediaSourceEventListener eventListener);
+
+  /**
    * Starts source preparation if not yet started, and adds a listener for timeline and/or manifest
    * updates.
    *

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

@@ -17,6 +17,7 @@ package com.google.android.exoplayer2.source;
 
 import android.os.Handler;
 import android.os.SystemClock;
+import android.support.annotation.CheckResult;
 import android.support.annotation.Nullable;
 import com.google.android.exoplayer2.C;
 import com.google.android.exoplayer2.Format;
@@ -24,6 +25,7 @@ import com.google.android.exoplayer2.Player;
 import com.google.android.exoplayer2.upstream.DataSpec;
 import com.google.android.exoplayer2.util.Assertions;
 import java.io.IOException;
+import java.util.concurrent.CopyOnWriteArrayList;
 
 /** Interface for callbacks to be notified of {@link MediaSource} events. */
 public interface MediaSourceEventListener {
@@ -190,30 +192,61 @@ public interface MediaSourceEventListener {
    */
   void onDownstreamFormatChanged(MediaLoadData mediaLoadData);
 
-  /** Dispatches events to a {@link MediaSourceEventListener}. */
+  /** Dispatches events to {@link MediaSourceEventListener}s. */
   final class EventDispatcher {
 
-    @Nullable private final Handler handler;
-    @Nullable private final MediaSourceEventListener listener;
+    private final CopyOnWriteArrayList<ListenerAndHandler> listenerAndHandlers;
     private final long mediaTimeOffsetMs;
 
-    public EventDispatcher(@Nullable Handler handler, @Nullable MediaSourceEventListener listener) {
-      this(handler, listener, 0);
+    /** Create event dispatcher. */
+    /* package */ EventDispatcher() {
+      this(
+          /* listenerAndHandlers= */ new CopyOnWriteArrayList<ListenerAndHandler>(),
+          /* mediaTimeOffsetMs= */ 0);
     }
 
-    public EventDispatcher(
-        @Nullable Handler handler,
-        @Nullable MediaSourceEventListener listener,
-        long mediaTimeOffsetMs) {
-      this.handler = listener != null ? Assertions.checkNotNull(handler) : null;
-      this.listener = listener;
+    private EventDispatcher(
+        CopyOnWriteArrayList<ListenerAndHandler> listenerAndHandlers, long mediaTimeOffsetMs) {
+      this.listenerAndHandlers = listenerAndHandlers;
       this.mediaTimeOffsetMs = mediaTimeOffsetMs;
     }
 
-    public EventDispatcher copyWithMediaTimeOffsetMs(long mediaTimeOffsetMs) {
-      return new EventDispatcher(handler, listener, mediaTimeOffsetMs);
+    /**
+     * Creates a view of the event dispatcher with a media time offset.
+     *
+     * @param mediaTimeOffsetMs The offset to be added to all media times, in milliseconds.
+     * @return A view of the event dispatcher with the added media time offset.
+     */
+    @CheckResult
+    public EventDispatcher withMediaTimeOffsetMs(long mediaTimeOffsetMs) {
+      return new EventDispatcher(listenerAndHandlers, mediaTimeOffsetMs);
+    }
+
+    /**
+     * Adds a listener to the event dispatcher.
+     *
+     * @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) {
+      Assertions.checkArgument(handler != null && eventListener != null);
+      listenerAndHandlers.add(new ListenerAndHandler(handler, eventListener));
+    }
+
+    /**
+     * Removes a listener from the event dispatcher.
+     *
+     * @param eventListener The listener to be removed.
+     */
+    public void removeEventListener(MediaSourceEventListener eventListener) {
+      for (ListenerAndHandler listenerAndHandler : listenerAndHandlers) {
+        if (listenerAndHandler.listener == eventListener) {
+          listenerAndHandlers.remove(listenerAndHandler);
+        }
+      }
     }
 
+    /** Dispatches {@link #onLoadStarted(LoadEventInfo, MediaLoadData)}. */
     public void loadStarted(DataSpec dataSpec, int dataType, long elapsedRealtimeMs) {
       loadStarted(
           dataSpec,
@@ -238,12 +271,12 @@ public interface MediaSourceEventListener {
         final long mediaStartTimeUs,
         final long mediaEndTimeUs,
         final long elapsedRealtimeMs) {
-      if (listener != null && handler != null) {
-        handler.post(
+      for (final ListenerAndHandler listenerAndHandler : listenerAndHandlers) {
+        listenerAndHandler.handler.post(
             new Runnable() {
               @Override
               public void run() {
-                listener.onLoadStarted(
+                listenerAndHandler.listener.onLoadStarted(
                     new LoadEventInfo(
                         dataSpec, elapsedRealtimeMs, /* loadDurationMs= */ 0, /* bytesLoaded= */ 0),
                     new MediaLoadData(
@@ -293,12 +326,12 @@ public interface MediaSourceEventListener {
         final long elapsedRealtimeMs,
         final long loadDurationMs,
         final long bytesLoaded) {
-      if (listener != null && handler != null) {
-        handler.post(
+      for (final ListenerAndHandler listenerAndHandler : listenerAndHandlers) {
+        listenerAndHandler.handler.post(
             new Runnable() {
               @Override
               public void run() {
-                listener.onLoadCompleted(
+                listenerAndHandler.listener.onLoadCompleted(
                     new LoadEventInfo(dataSpec, elapsedRealtimeMs, loadDurationMs, bytesLoaded),
                     new MediaLoadData(
                         dataType,
@@ -347,12 +380,12 @@ public interface MediaSourceEventListener {
         final long elapsedRealtimeMs,
         final long loadDurationMs,
         final long bytesLoaded) {
-      if (listener != null && handler != null) {
-        handler.post(
+      for (final ListenerAndHandler listenerAndHandler : listenerAndHandlers) {
+        listenerAndHandler.handler.post(
             new Runnable() {
               @Override
               public void run() {
-                listener.onLoadCanceled(
+                listenerAndHandler.listener.onLoadCanceled(
                     new LoadEventInfo(dataSpec, elapsedRealtimeMs, loadDurationMs, bytesLoaded),
                     new MediaLoadData(
                         dataType,
@@ -407,12 +440,12 @@ public interface MediaSourceEventListener {
         final long bytesLoaded,
         final IOException error,
         final boolean wasCanceled) {
-      if (listener != null && handler != null) {
-        handler.post(
+      for (final ListenerAndHandler listenerAndHandler : listenerAndHandlers) {
+        listenerAndHandler.handler.post(
             new Runnable() {
               @Override
               public void run() {
-                listener.onLoadError(
+                listenerAndHandler.listener.onLoadError(
                     new LoadEventInfo(dataSpec, elapsedRealtimeMs, loadDurationMs, bytesLoaded),
                     new MediaLoadData(
                         dataType,
@@ -432,12 +465,12 @@ public interface MediaSourceEventListener {
     /** Dispatches {@link #onUpstreamDiscarded(MediaLoadData)}. */
     public void upstreamDiscarded(
         final int trackType, final long mediaStartTimeUs, final long mediaEndTimeUs) {
-      if (listener != null && handler != null) {
-        handler.post(
+      for (final ListenerAndHandler listenerAndHandler : listenerAndHandlers) {
+        listenerAndHandler.handler.post(
             new Runnable() {
               @Override
               public void run() {
-                listener.onUpstreamDiscarded(
+                listenerAndHandler.listener.onUpstreamDiscarded(
                     new MediaLoadData(
                         C.DATA_TYPE_MEDIA,
                         trackType,
@@ -458,12 +491,12 @@ public interface MediaSourceEventListener {
         final int trackSelectionReason,
         final @Nullable Object trackSelectionData,
         final long mediaTimeUs) {
-      if (listener != null && handler != null) {
-        handler.post(
+      for (final ListenerAndHandler listenerAndHandler : listenerAndHandlers) {
+        listenerAndHandler.handler.post(
             new Runnable() {
               @Override
               public void run() {
-                listener.onDownstreamFormatChanged(
+                listenerAndHandler.listener.onDownstreamFormatChanged(
                     new MediaLoadData(
                         C.DATA_TYPE_MEDIA,
                         trackType,
@@ -481,5 +514,16 @@ public interface MediaSourceEventListener {
       long mediaTimeMs = C.usToMs(mediaTimeUs);
       return mediaTimeMs == C.TIME_UNSET ? C.TIME_UNSET : mediaTimeOffsetMs + mediaTimeMs;
     }
+
+    private static final class ListenerAndHandler {
+
+      public final Handler handler;
+      public final MediaSourceEventListener listener;
+
+      public ListenerAndHandler(Handler handler, MediaSourceEventListener listener) {
+        this.handler = handler;
+        this.listener = listener;
+      }
+    }
   }
 }

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

@@ -21,7 +21,6 @@ import android.support.annotation.Nullable;
 import com.google.android.exoplayer2.ExoPlayer;
 import com.google.android.exoplayer2.Format;
 import com.google.android.exoplayer2.Timeline;
-import com.google.android.exoplayer2.source.MediaSourceEventListener.EventDispatcher;
 import com.google.android.exoplayer2.upstream.Allocator;
 import com.google.android.exoplayer2.upstream.DataSource;
 import com.google.android.exoplayer2.upstream.DataSpec;
@@ -102,8 +101,7 @@ public final class SingleSampleMediaSource extends BaseMediaSource {
     }
 
     /**
-     * Returns a new {@link ExtractorMediaSource} using the current parameters. Media source events
-     * will not be delivered.
+     * Returns a new {@link ExtractorMediaSource} using the current parameters.
      *
      * @param uri The {@link Uri}.
      * @param format The {@link Format} of the media stream.
@@ -111,35 +109,32 @@ public final class SingleSampleMediaSource extends BaseMediaSource {
      * @return The new {@link ExtractorMediaSource}.
      */
     public SingleSampleMediaSource createMediaSource(Uri uri, Format format, long durationUs) {
-      return createMediaSource(uri, format, durationUs, null, null);
+      isCreateCalled = true;
+      return new SingleSampleMediaSource(
+          uri,
+          dataSourceFactory,
+          format,
+          durationUs,
+          minLoadableRetryCount,
+          treatLoadErrorsAsEndOfStream);
     }
 
     /**
-     * Returns a new {@link SingleSampleMediaSource} using the current parameters.
-     *
-     * @param uri The {@link Uri}.
-     * @param format The {@link Format} of the media stream.
-     * @param durationUs The duration of the media stream in microseconds.
-     * @param eventHandler A handler for events.
-     * @param eventListener A listener of events., Format format, long durationUs
-     * @return The newly built {@link SingleSampleMediaSource}.
+     * @deprecated Use {@link #createMediaSource(Uri, Format, long)} and {@link
+     *     #addEventListener(Handler, MediaSourceEventListener)} instead.
      */
+    @Deprecated
     public SingleSampleMediaSource createMediaSource(
         Uri uri,
         Format format,
         long durationUs,
         @Nullable Handler eventHandler,
         @Nullable MediaSourceEventListener eventListener) {
-      isCreateCalled = true;
-      return new SingleSampleMediaSource(
-          uri,
-          dataSourceFactory,
-          format,
-          durationUs,
-          minLoadableRetryCount,
-          eventHandler,
-          eventListener,
-          treatLoadErrorsAsEndOfStream);
+      SingleSampleMediaSource mediaSource = createMediaSource(uri, format, durationUs);
+      if (eventHandler != null && eventListener != null) {
+        mediaSource.addEventListener(eventHandler, eventListener);
+      }
+      return mediaSource;
     }
 
   }
@@ -188,7 +183,13 @@ public final class SingleSampleMediaSource extends BaseMediaSource {
       Format format,
       long durationUs,
       int minLoadableRetryCount) {
-    this(uri, dataSourceFactory, format, durationUs, minLoadableRetryCount, null, null, false);
+    this(
+        uri,
+        dataSourceFactory,
+        format,
+        durationUs,
+        minLoadableRetryCount,
+        /* treatLoadErrorsAsEndOfStream= */ false);
   }
 
   /**
@@ -223,9 +224,10 @@ public final class SingleSampleMediaSource extends BaseMediaSource {
         format,
         durationUs,
         minLoadableRetryCount,
-        eventHandler,
-        eventListener == null ? null : new EventListenerWrapper(eventListener, eventSourceId),
         treatLoadErrorsAsEndOfStream);
+    if (eventHandler != null && eventListener != null) {
+      addEventListener(eventHandler, new EventListenerWrapper(eventListener, eventSourceId));
+    }
   }
 
   private SingleSampleMediaSource(
@@ -234,15 +236,13 @@ public final class SingleSampleMediaSource extends BaseMediaSource {
       Format format,
       long durationUs,
       int minLoadableRetryCount,
-      Handler eventHandler,
-      MediaSourceEventListener eventListener,
       boolean treatLoadErrorsAsEndOfStream) {
     this.dataSourceFactory = dataSourceFactory;
     this.format = format;
     this.durationUs = durationUs;
     this.minLoadableRetryCount = minLoadableRetryCount;
     this.treatLoadErrorsAsEndOfStream = treatLoadErrorsAsEndOfStream;
-    this.eventDispatcher = new EventDispatcher(eventHandler, eventListener);
+    this.eventDispatcher = getEventDispatcher();
     dataSpec = new DataSpec(uri);
     timeline = new SinglePeriodTimeline(durationUs, true, false);
   }

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

@@ -51,13 +51,9 @@ public final class AdsMediaSource extends CompositeMediaSource<MediaPeriodId> {
      * Creates a new {@link MediaSource} for loading the ad media with the specified {@code uri}.
      *
      * @param uri The URI of the media or manifest to play.
-     * @param handler A handler for listener events. May be null if delivery of events is not
-     *     required.
-     * @param listener A listener for events. May be null if delivery of events is not required.
      * @return The new media source.
      */
-    MediaSource createMediaSource(
-        Uri uri, @Nullable Handler handler, @Nullable MediaSourceEventListener listener);
+    MediaSource createMediaSource(Uri uri);
 
     /**
      * Returns the content types supported by media sources created by this factory. Each element
@@ -224,8 +220,8 @@ public final class AdsMediaSource extends CompositeMediaSource<MediaPeriodId> {
       int adIndexInAdGroup = id.adIndexInAdGroup;
       if (adGroupMediaSources[adGroupIndex].length <= adIndexInAdGroup) {
         Uri adUri = adPlaybackState.adGroups[id.adGroupIndex].uris[id.adIndexInAdGroup];
-        MediaSource adMediaSource =
-            adMediaSourceFactory.createMediaSource(adUri, eventHandler, eventListener);
+        MediaSource adMediaSource = adMediaSourceFactory.createMediaSource(adUri);
+        adMediaSource.addEventListener(eventHandler, eventListener);
         int oldAdCount = adGroupMediaSources[id.adGroupIndex].length;
         if (adIndexInAdGroup >= oldAdCount) {
           int adCount = adIndexInAdGroup + 1;

library/dash/src/main/java/com/google/android/exoplayer2/source/dash/DashMediaSource.java

@@ -167,15 +167,10 @@ public final class DashMediaSource extends BaseMediaSource {
      * sideloaded manifest.
      *
      * @param manifest The manifest. {@link DashManifest#dynamic} must be false.
-     * @param eventHandler A handler for events.
-     * @param eventListener A listener of events.
      * @return The new {@link DashMediaSource}.
      * @throws IllegalArgumentException If {@link DashManifest#dynamic} is true.
      */
-    public DashMediaSource createMediaSource(
-        DashManifest manifest,
-        @Nullable Handler eventHandler,
-        @Nullable MediaSourceEventListener eventListener) {
+    public DashMediaSource createMediaSource(DashManifest manifest) {
       Assertions.checkArgument(!manifest.dynamic);
       isCreateCalled = true;
       return new DashMediaSource(
@@ -186,35 +181,33 @@ public final class DashMediaSource extends BaseMediaSource {
           chunkSourceFactory,
           compositeSequenceableLoaderFactory,
           minLoadableRetryCount,
-          livePresentationDelayMs,
-          eventHandler,
-          eventListener);
+          livePresentationDelayMs);
     }
 
     /**
-     * Returns a new {@link DashMediaSource} using the current parameters. Media source events will
-     * not be delivered.
-     *
-     * @param manifestUri The manifest {@link Uri}.
-     * @return The new {@link DashMediaSource}.
+     * @deprecated Use {@link #createMediaSource(DashManifest)} and {@link
+     *     #addEventListener(Handler, MediaSourceEventListener)} instead.
      */
-    public DashMediaSource createMediaSource(Uri manifestUri) {
-      return createMediaSource(manifestUri, null, null);
+    @Deprecated
+    public DashMediaSource createMediaSource(
+        DashManifest manifest,
+        @Nullable Handler eventHandler,
+        @Nullable MediaSourceEventListener eventListener) {
+      DashMediaSource mediaSource = createMediaSource(manifest);
+      if (eventHandler != null && eventListener != null) {
+        mediaSource.addEventListener(eventHandler, eventListener);
+      }
+      return mediaSource;
     }
 
     /**
      * Returns a new {@link DashMediaSource} using the current parameters.
      *
      * @param manifestUri The manifest {@link Uri}.
-     * @param eventHandler A handler for events.
-     * @param eventListener A listener of events.
      * @return The new {@link DashMediaSource}.
      */
     @Override
-    public DashMediaSource createMediaSource(
-        Uri manifestUri,
-        @Nullable Handler eventHandler,
-        @Nullable MediaSourceEventListener eventListener) {
+    public DashMediaSource createMediaSource(Uri manifestUri) {
       isCreateCalled = true;
       if (manifestParser == null) {
         manifestParser = new DashManifestParser();
@@ -227,9 +220,23 @@ public final class DashMediaSource extends BaseMediaSource {
           chunkSourceFactory,
           compositeSequenceableLoaderFactory,
           minLoadableRetryCount,
-          livePresentationDelayMs,
-          eventHandler,
-          eventListener);
+          livePresentationDelayMs);
+    }
+
+    /**
+     * @deprecated Use {@link #createMediaSource(Uri)} and {@link #addEventListener(Handler,
+     *     MediaSourceEventListener)} instead.
+     */
+    @Deprecated
+    public DashMediaSource createMediaSource(
+        Uri manifestUri,
+        @Nullable Handler eventHandler,
+        @Nullable MediaSourceEventListener eventListener) {
+      DashMediaSource mediaSource = createMediaSource(manifestUri);
+      if (eventHandler != null && eventListener != null) {
+        mediaSource.addEventListener(eventHandler, eventListener);
+      }
+      return mediaSource;
     }
 
     @Override
@@ -340,9 +347,18 @@ public final class DashMediaSource extends BaseMediaSource {
       int minLoadableRetryCount,
       Handler eventHandler,
       MediaSourceEventListener eventListener) {
-    this(manifest, null, null, null, chunkSourceFactory,
-        new DefaultCompositeSequenceableLoaderFactory(), minLoadableRetryCount,
-        DEFAULT_LIVE_PRESENTATION_DELAY_PREFER_MANIFEST_MS, eventHandler, eventListener);
+    this(
+        manifest,
+        null,
+        null,
+        null,
+        chunkSourceFactory,
+        new DefaultCompositeSequenceableLoaderFactory(),
+        minLoadableRetryCount,
+        DEFAULT_LIVE_PRESENTATION_DELAY_PREFER_MANIFEST_MS);
+    if (eventHandler != null && eventListener != null) {
+      addEventListener(eventHandler, eventListener);
+    }
   }
 
   /**
@@ -427,9 +443,18 @@ public final class DashMediaSource extends BaseMediaSource {
       long livePresentationDelayMs,
       Handler eventHandler,
       MediaSourceEventListener eventListener) {
-    this(null, manifestUri, manifestDataSourceFactory, manifestParser, chunkSourceFactory,
-        new DefaultCompositeSequenceableLoaderFactory(), minLoadableRetryCount,
-        livePresentationDelayMs, eventHandler, eventListener);
+    this(
+        null,
+        manifestUri,
+        manifestDataSourceFactory,
+        manifestParser,
+        chunkSourceFactory,
+        new DefaultCompositeSequenceableLoaderFactory(),
+        minLoadableRetryCount,
+        livePresentationDelayMs);
+    if (eventHandler != null && eventListener != null) {
+      addEventListener(eventHandler, eventListener);
+    }
   }
 
   private DashMediaSource(
@@ -440,9 +465,7 @@ public final class DashMediaSource extends BaseMediaSource {
       DashChunkSource.Factory chunkSourceFactory,
       CompositeSequenceableLoaderFactory compositeSequenceableLoaderFactory,
       int minLoadableRetryCount,
-      long livePresentationDelayMs,
-      Handler eventHandler,
-      MediaSourceEventListener eventListener) {
+      long livePresentationDelayMs) {
     this.initialManifestUri = manifestUri;
     this.manifest = manifest;
     this.manifestUri = manifestUri;
@@ -453,7 +476,7 @@ public final class DashMediaSource extends BaseMediaSource {
     this.livePresentationDelayMs = livePresentationDelayMs;
     this.compositeSequenceableLoaderFactory = compositeSequenceableLoaderFactory;
     sideloadedManifest = manifest != null;
-    eventDispatcher = new EventDispatcher(eventHandler, eventListener);
+    eventDispatcher = getEventDispatcher();
     manifestUriLock = new Object();
     periodsById = new SparseArray<>();
     playerEmsgCallback = new DefaultPlayerEmsgCallback();
@@ -516,8 +539,8 @@ public final class DashMediaSource extends BaseMediaSource {
   @Override
   public MediaPeriod createPeriod(MediaPeriodId periodId, Allocator allocator) {
     int periodIndex = periodId.periodIndex;
-    EventDispatcher periodEventDispatcher = eventDispatcher.copyWithMediaTimeOffsetMs(
-        manifest.getPeriod(periodIndex).startMs);
+    EventDispatcher periodEventDispatcher =
+        eventDispatcher.withMediaTimeOffsetMs(manifest.getPeriod(periodIndex).startMs);
     DashMediaPeriod mediaPeriod =
         new DashMediaPeriod(
             firstPeriodId + periodIndex,

library/hls/src/main/java/com/google/android/exoplayer2/source/hls/HlsMediaSource.java

@@ -164,28 +164,12 @@ public final class HlsMediaSource extends BaseMediaSource
     }
 
     /**
-     * Returns a new {@link HlsMediaSource} using the current parameters. Media source events will
-     * not be delivered.
-     *
-     * @return The new {@link HlsMediaSource}.
-     */
-    public HlsMediaSource createMediaSource(Uri playlistUri) {
-      return createMediaSource(playlistUri, null, null);
-    }
-
-    /**
      * Returns a new {@link HlsMediaSource} using the current parameters.
      *
-     * @param playlistUri The playlist {@link Uri}.
-     * @param eventHandler A handler for events.
-     * @param eventListener A listener of events.
      * @return The new {@link HlsMediaSource}.
      */
     @Override
-    public HlsMediaSource createMediaSource(
-        Uri playlistUri,
-        @Nullable Handler eventHandler,
-        @Nullable MediaSourceEventListener eventListener) {
+    public HlsMediaSource createMediaSource(Uri playlistUri) {
       isCreateCalled = true;
       if (playlistParser == null) {
         playlistParser = new HlsPlaylistParser();
@@ -196,12 +180,26 @@ public final class HlsMediaSource extends BaseMediaSource
           extractorFactory,
           compositeSequenceableLoaderFactory,
           minLoadableRetryCount,
-          eventHandler,
-          eventListener,
           playlistParser,
           allowChunklessPreparation);
     }
 
+    /**
+     * @deprecated Use {@link #createMediaSource(Uri)} and {@link #addEventListener(Handler,
+     *     MediaSourceEventListener)} instead.
+     */
+    @Deprecated
+    public HlsMediaSource createMediaSource(
+        Uri playlistUri,
+        @Nullable Handler eventHandler,
+        @Nullable MediaSourceEventListener eventListener) {
+      HlsMediaSource mediaSource = createMediaSource(playlistUri);
+      if (eventHandler != null && eventListener != null) {
+        mediaSource.addEventListener(eventHandler, eventListener);
+      }
+      return mediaSource;
+    }
+
     @Override
     public int[] getSupportedTypes() {
       return new int[] {C.TYPE_HLS};
@@ -294,10 +292,11 @@ public final class HlsMediaSource extends BaseMediaSource
         extractorFactory,
         new DefaultCompositeSequenceableLoaderFactory(),
         minLoadableRetryCount,
-        eventHandler,
-        eventListener,
         playlistParser,
         false);
+    if (eventHandler != null && eventListener != null) {
+      addEventListener(eventHandler, eventListener);
+    }
   }
 
   private HlsMediaSource(
@@ -306,8 +305,6 @@ public final class HlsMediaSource extends BaseMediaSource
       HlsExtractorFactory extractorFactory,
       CompositeSequenceableLoaderFactory compositeSequenceableLoaderFactory,
       int minLoadableRetryCount,
-      Handler eventHandler,
-      MediaSourceEventListener eventListener,
       ParsingLoadable.Parser<HlsPlaylist> playlistParser,
       boolean allowChunklessPreparation) {
     this.manifestUri = manifestUri;
@@ -317,7 +314,7 @@ public final class HlsMediaSource extends BaseMediaSource
     this.minLoadableRetryCount = minLoadableRetryCount;
     this.playlistParser = playlistParser;
     this.allowChunklessPreparation = allowChunklessPreparation;
-    eventDispatcher = new EventDispatcher(eventHandler, eventListener);
+    eventDispatcher = getEventDispatcher();
   }
 
   @Override

library/smoothstreaming/src/main/java/com/google/android/exoplayer2/source/smoothstreaming/SsMediaSource.java

@@ -153,15 +153,10 @@ public final class SsMediaSource extends BaseMediaSource
      * manifest.
      *
      * @param manifest The manifest. {@link SsManifest#isLive} must be false.
-     * @param eventHandler A handler for events.
-     * @param eventListener A listener of events.
      * @return The new {@link SsMediaSource}.
      * @throws IllegalArgumentException If {@link SsManifest#isLive} is true.
      */
-    public SsMediaSource createMediaSource(
-        SsManifest manifest,
-        @Nullable Handler eventHandler,
-        @Nullable MediaSourceEventListener eventListener) {
+    public SsMediaSource createMediaSource(SsManifest manifest) {
       Assertions.checkArgument(!manifest.isLive);
       isCreateCalled = true;
       return new SsMediaSource(
@@ -172,35 +167,33 @@ public final class SsMediaSource extends BaseMediaSource
           chunkSourceFactory,
           compositeSequenceableLoaderFactory,
           minLoadableRetryCount,
-          livePresentationDelayMs,
-          eventHandler,
-          eventListener);
+          livePresentationDelayMs);
     }
 
     /**
-     * Returns a new {@link SsMediaSource} using the current parameters. Media source events will
-     * not be delivered.
-     *
-     * @param manifestUri The manifest {@link Uri}.
-     * @return The new {@link SsMediaSource}.
+     * @deprecated Use {@link #createMediaSource(SsManifest)} and {@link #addEventListener(Handler,
+     *     MediaSourceEventListener)} instead.
      */
-    public SsMediaSource createMediaSource(Uri manifestUri) {
-      return createMediaSource(manifestUri, null, null);
+    @Deprecated
+    public SsMediaSource createMediaSource(
+        SsManifest manifest,
+        @Nullable Handler eventHandler,
+        @Nullable MediaSourceEventListener eventListener) {
+      SsMediaSource mediaSource = createMediaSource(manifest);
+      if (eventHandler != null && eventListener != null) {
+        mediaSource.addEventListener(eventHandler, eventListener);
+      }
+      return mediaSource;
     }
 
     /**
      * Returns a new {@link SsMediaSource} using the current parameters.
      *
      * @param manifestUri The manifest {@link Uri}.
-     * @param eventHandler A handler for events.
-     * @param eventListener A listener of events.
      * @return The new {@link SsMediaSource}.
      */
     @Override
-    public SsMediaSource createMediaSource(
-        Uri manifestUri,
-        @Nullable Handler eventHandler,
-        @Nullable MediaSourceEventListener eventListener) {
+    public SsMediaSource createMediaSource(Uri manifestUri) {
       isCreateCalled = true;
       if (manifestParser == null) {
         manifestParser = new SsManifestParser();
@@ -213,9 +206,23 @@ public final class SsMediaSource extends BaseMediaSource
           chunkSourceFactory,
           compositeSequenceableLoaderFactory,
           minLoadableRetryCount,
-          livePresentationDelayMs,
-          eventHandler,
-          eventListener);
+          livePresentationDelayMs);
+    }
+
+    /**
+     * @deprecated Use {@link #createMediaSource(Uri)} and {@link #addEventListener(Handler,
+     *     MediaSourceEventListener)} instead.
+     */
+    @Deprecated
+    public SsMediaSource createMediaSource(
+        Uri manifestUri,
+        @Nullable Handler eventHandler,
+        @Nullable MediaSourceEventListener eventListener) {
+      SsMediaSource mediaSource = createMediaSource(manifestUri);
+      if (eventHandler != null && eventListener != null) {
+        mediaSource.addEventListener(eventHandler, eventListener);
+      }
+      return mediaSource;
     }
 
     @Override
@@ -300,9 +307,18 @@ public final class SsMediaSource extends BaseMediaSource
       int minLoadableRetryCount,
       Handler eventHandler,
       MediaSourceEventListener eventListener) {
-    this(manifest, null, null, null, chunkSourceFactory,
-        new DefaultCompositeSequenceableLoaderFactory(), minLoadableRetryCount,
-        DEFAULT_LIVE_PRESENTATION_DELAY_MS, eventHandler, eventListener);
+    this(
+        manifest,
+        null,
+        null,
+        null,
+        chunkSourceFactory,
+        new DefaultCompositeSequenceableLoaderFactory(),
+        minLoadableRetryCount,
+        DEFAULT_LIVE_PRESENTATION_DELAY_MS);
+    if (eventHandler != null && eventListener != null) {
+      addEventListener(eventHandler, eventListener);
+    }
   }
 
   /**
@@ -383,9 +399,18 @@ public final class SsMediaSource extends BaseMediaSource
       long livePresentationDelayMs,
       Handler eventHandler,
       MediaSourceEventListener eventListener) {
-    this(null, manifestUri, manifestDataSourceFactory, manifestParser, chunkSourceFactory,
-        new DefaultCompositeSequenceableLoaderFactory(), minLoadableRetryCount,
-        livePresentationDelayMs, eventHandler, eventListener);
+    this(
+        null,
+        manifestUri,
+        manifestDataSourceFactory,
+        manifestParser,
+        chunkSourceFactory,
+        new DefaultCompositeSequenceableLoaderFactory(),
+        minLoadableRetryCount,
+        livePresentationDelayMs);
+    if (eventHandler != null && eventListener != null) {
+      addEventListener(eventHandler, eventListener);
+    }
   }
 
   private SsMediaSource(
@@ -396,9 +421,7 @@ public final class SsMediaSource extends BaseMediaSource
       SsChunkSource.Factory chunkSourceFactory,
       CompositeSequenceableLoaderFactory compositeSequenceableLoaderFactory,
       int minLoadableRetryCount,
-      long livePresentationDelayMs,
-      Handler eventHandler,
-      MediaSourceEventListener eventListener) {
+      long livePresentationDelayMs) {
     Assertions.checkState(manifest == null || !manifest.isLive);
     this.manifest = manifest;
     this.manifestUri = manifestUri == null ? null : SsUtil.fixManifestUri(manifestUri);
@@ -408,7 +431,7 @@ public final class SsMediaSource extends BaseMediaSource
     this.compositeSequenceableLoaderFactory = compositeSequenceableLoaderFactory;
     this.minLoadableRetryCount = minLoadableRetryCount;
     this.livePresentationDelayMs = livePresentationDelayMs;
-    this.eventDispatcher = new EventDispatcher(eventHandler, eventListener);
+    this.eventDispatcher = getEventDispatcher();
     sideloadedManifest = manifest != null;
     mediaPeriods = new ArrayList<>();
   }

testutils/src/main/java/com/google/android/exoplayer2/testutil/FakeAdaptiveMediaSource.java

@@ -20,7 +20,6 @@ import com.google.android.exoplayer2.Timeline;
 import com.google.android.exoplayer2.Timeline.Period;
 import com.google.android.exoplayer2.source.MediaSource;
 import com.google.android.exoplayer2.source.MediaSourceEventListener;
-import com.google.android.exoplayer2.source.MediaSourceEventListener.EventDispatcher;
 import com.google.android.exoplayer2.source.TrackGroupArray;
 import com.google.android.exoplayer2.upstream.Allocator;
 
@@ -30,7 +29,6 @@ import com.google.android.exoplayer2.upstream.Allocator;
  */
 public class FakeAdaptiveMediaSource extends FakeMediaSource {
 
-  private final EventDispatcher eventDispatcher;
   private final FakeChunkSource.Factory chunkSourceFactory;
 
   public FakeAdaptiveMediaSource(
@@ -41,16 +39,16 @@ public class FakeAdaptiveMediaSource extends FakeMediaSource {
       MediaSourceEventListener eventListener,
       FakeChunkSource.Factory chunkSourceFactory) {
     super(timeline, manifest, trackGroupArray);
-    this.eventDispatcher = new EventDispatcher(eventHandler, eventListener);
     this.chunkSourceFactory = chunkSourceFactory;
+    addEventListener(eventHandler, eventListener);
   }
 
   @Override
   protected FakeMediaPeriod createFakeMediaPeriod(MediaPeriodId id, TrackGroupArray trackGroupArray,
       Allocator allocator) {
     Period period = timeline.getPeriod(id.periodIndex, new Period());
-    return new FakeAdaptiveMediaPeriod(trackGroupArray, eventDispatcher, allocator,
-        chunkSourceFactory, period.durationUs);
+    return new FakeAdaptiveMediaPeriod(
+        trackGroupArray, getEventDispatcher(), allocator, chunkSourceFactory, period.durationUs);
   }
 
 }