Propagate audioSessionId.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=127300225

demo/src/main/java/com/google/android/exoplayer2/demo/EventLogger.java

@@ -149,6 +149,11 @@ public class EventLogger implements ExoPlayer.EventListener, SimpleExoPlayer.Deb
     Log.d(TAG, "audioEnabled [" + getSessionTimeString() + "]");
   }
 
+  @Override
+  public void onAudioSessionId(int audioSessionId) {
+    Log.d(TAG, "audioSessionId [" + audioSessionId + "]");
+  }
+
   @Override
   public void onAudioDecoderInitialized(String decoderName, long elapsedRealtimeMs,
       long initializationDurationMs) {

library/src/main/java/com/google/android/exoplayer2/AudioRendererEventListener.java

@@ -34,6 +34,13 @@ public interface AudioRendererEventListener {
    */
   void onAudioEnabled(CodecCounters counters);
 
+  /**
+   * Invoked when the audio session is set.
+   *
+   * @param audioSessionId The audio session id.
+   */
+  void onAudioSessionId(int audioSessionId);
+
   /**
    * Invoked when a decoder is created.
    *
@@ -142,6 +149,17 @@ public interface AudioRendererEventListener {
       }
     }
 
+    public void audioSessionId(final int audioSessionId) {
+      if (listener != null) {
+        handler.post(new Runnable() {
+          @Override
+          public void run() {
+            listener.onAudioSessionId(audioSessionId);
+          }
+        });
+      }
+    }
+    
   }
 
 }

library/src/main/java/com/google/android/exoplayer2/MediaCodecAudioRenderer.java

@@ -338,6 +338,7 @@ public class MediaCodecAudioRenderer extends MediaCodecRenderer implements Media
           audioTrack.initialize(audioSessionId);
         } else {
           audioSessionId = audioTrack.initialize();
+          eventDispatcher.audioSessionId(audioSessionId);
           onAudioSessionId(audioSessionId);
         }
         audioTrackHasData = false;

library/src/main/java/com/google/android/exoplayer2/SimpleExoPlayer.java

@@ -16,6 +16,7 @@
 package com.google.android.exoplayer2;
 
 import com.google.android.exoplayer2.audio.AudioCapabilities;
+import com.google.android.exoplayer2.audio.AudioTrack;
 import com.google.android.exoplayer2.drm.DrmSessionManager;
 import com.google.android.exoplayer2.metadata.MetadataRenderer;
 import com.google.android.exoplayer2.metadata.id3.Id3Frame;
@@ -62,6 +63,7 @@ public final class SimpleExoPlayer implements ExoPlayer {
    */
   public interface DebugListener {
     void onAudioEnabled(CodecCounters counters);
+    void onAudioSessionId(int audioSessionId);
     void onAudioDecoderInitialized(String decoderName, long elapsedRealtimeMs,
         long initializationDurationMs);
     void onAudioFormatChanged(Format format);
@@ -109,6 +111,7 @@ public final class SimpleExoPlayer implements ExoPlayer {
   private DebugListener debugListener;
   private CodecCounters videoCodecCounters;
   private CodecCounters audioCodecCounters;
+  private int audioSessionId;
 
   /* package */ SimpleExoPlayer(Context context, TrackSelector trackSelector,
       LoadControl loadControl, DrmSessionManager drmSessionManager,
@@ -143,6 +146,7 @@ public final class SimpleExoPlayer implements ExoPlayer {
     }
     this.videoRendererCount = videoRendererCount;
     this.audioRendererCount = audioRendererCount;
+    this.audioSessionId = AudioTrack.SESSION_ID_NOT_SET;
 
     // Build the player and associated objects.
     player = new ExoPlayerImpl(renderers, trackSelector, loadControl);
@@ -244,6 +248,14 @@ public final class SimpleExoPlayer implements ExoPlayer {
     return audioFormat;
   }
 
+  /**
+   * @return The audio session identifier. If not set {@code AudioTrack.SESSION_ID_NOT_SET} is
+   *     returned.
+   */
+  public int getAudioSessionId() {
+    return audioSessionId;
+  }
+
   /**
    * @return The {@link CodecCounters} for video, or null if there is no video component to the
    *     current media.
@@ -547,6 +559,14 @@ public final class SimpleExoPlayer implements ExoPlayer {
       }
     }
 
+    @Override
+    public void onAudioSessionId(int sessionId) {
+      audioSessionId = sessionId;
+      if (debugListener != null) {
+        debugListener.onAudioSessionId(sessionId);
+      }
+    }
+
     @Override
     public void onAudioDecoderInitialized(String decoderName, long initializedTimestampMs,
         long initializationDurationMs) {
@@ -579,6 +599,7 @@ public final class SimpleExoPlayer implements ExoPlayer {
       }
       audioFormat = null;
       audioCodecCounters = null;
+      audioSessionId = AudioTrack.SESSION_ID_NOT_SET;
     }
 
     // TextRendererOutput implementation

library/src/main/java/com/google/android/exoplayer2/extensions/AudioDecoderRenderer.java

@@ -189,6 +189,7 @@ public abstract class AudioDecoderRenderer extends Renderer implements MediaCloc
         audioTrack.initialize(audioSessionId);
       } else {
         audioSessionId = audioTrack.initialize();
+        eventDispatcher.audioSessionId(audioSessionId);
         onAudioSessionId(audioSessionId);
       }
       audioTrackHasData = false;

playbacktests/src/main/java/com/google/android/exoplayer2/playbacktests/util/ExoHostedTest.java

@@ -220,6 +220,11 @@ public abstract class ExoHostedTest implements HostedTest, ExoPlayer.EventListen
     Log.d(tag, "audioEnabled");
   }
 
+  @Override
+  public void onAudioSessionId(int audioSessionId) {
+    Log.d(tag, "audioSessionId [" + audioSessionId + "]");
+  }
+
   @Override
   public void onAudioDecoderInitialized(String decoderName, long elapsedRealtimeMs,
       long initializationDurationMs) {