Separate enabling/setting TrackStreams in renderers (playlists #1).

This is in preparation for changing the TrackStream while keeping the renderer
enabled, to give seamless transitions for playlists.
-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=123394733

extensions/vp9/src/main/java/com/google/android/exoplayer/ext/vp9/LibvpxVideoTrackRenderer.java

@@ -332,7 +332,7 @@ public final class LibvpxVideoTrackRenderer extends TrackRenderer {
   }
 
   @Override
-  protected void onEnabled(Format[] formats, boolean joining) throws ExoPlaybackException {
+  protected void onEnabled(boolean joining) throws ExoPlaybackException {
     codecCounters.reset();
     eventDispatcher.enabled(codecCounters);
   }

library/src/main/java/com/google/android/exoplayer/MediaCodecAudioTrackRenderer.java

@@ -255,10 +255,10 @@ public class MediaCodecAudioTrackRenderer extends MediaCodecTrackRenderer implem
   }
 
   @Override
-  protected void onEnabled(Format[] formats, boolean joining) throws ExoPlaybackException {
+  protected void onEnabled(boolean joining) throws ExoPlaybackException {
     codecCounters.reset();
     eventDispatcher.enabled(codecCounters);
-    super.onEnabled(formats, joining);
+    super.onEnabled(joining);
   }
 
   @Override

library/src/main/java/com/google/android/exoplayer/MediaCodecVideoTrackRenderer.java

@@ -209,10 +209,18 @@ public class MediaCodecVideoTrackRenderer extends MediaCodecTrackRenderer {
   }
 
   @Override
-  protected void onEnabled(Format[] formats, boolean joining) throws ExoPlaybackException {
+  protected void onEnabled(boolean joining) throws ExoPlaybackException {
     codecCounters.reset();
     eventDispatcher.enabled(codecCounters);
-    super.onEnabled(formats, joining);
+    super.onEnabled(joining);
+    if (joining && allowedJoiningTimeMs > 0) {
+      joiningDeadlineMs = SystemClock.elapsedRealtime() + allowedJoiningTimeMs;
+    }
+    frameReleaseTimeHelper.enable();
+  }
+
+  @Override
+  protected void onStreamChanged(Format[] formats) throws ExoPlaybackException {
     adaptiveMaxWidth = Format.NO_VALUE;
     adaptiveMaxHeight = Format.NO_VALUE;
     if (formats.length > 1) {
@@ -226,10 +234,7 @@ public class MediaCodecVideoTrackRenderer extends MediaCodecTrackRenderer {
         adaptiveMaxHeight = 1080;
       }
     }
-    if (joining && allowedJoiningTimeMs > 0) {
-      joiningDeadlineMs = SystemClock.elapsedRealtime() + allowedJoiningTimeMs;
-    }
-    frameReleaseTimeHelper.enable();
+    super.onStreamChanged(formats);
   }
 
   @Override

library/src/main/java/com/google/android/exoplayer/TrackRenderer.java

@@ -174,8 +174,8 @@ public abstract class TrackRenderer implements ExoPlayerComponent {
       boolean joining) throws ExoPlaybackException {
     Assertions.checkState(state == STATE_DISABLED);
     state = STATE_ENABLED;
-    this.stream = stream;
-    onEnabled(formats, joining);
+    onEnabled(joining);
+    replaceTrackStream(formats, stream);
     reset(positionUs);
   }
 
@@ -184,11 +184,35 @@ public abstract class TrackRenderer implements ExoPlayerComponent {
    * <p>
    * The default implementation is a no-op.
    *
-   * @param formats The enabled formats.
    * @param joining Whether this renderer is being enabled to join an ongoing playback.
    * @throws ExoPlaybackException If an error occurs.
    */
-  protected void onEnabled(Format[] formats, boolean joining) throws ExoPlaybackException {
+  protected void onEnabled(boolean joining) throws ExoPlaybackException {
+    // Do nothing.
+  }
+
+  /**
+   * Replaces the {@link TrackStream} from which samples will be consumed.
+   *
+   * @param formats The enabled formats.
+   * @param trackStream The track stream from which the renderer should consume.
+   * @throws ExoPlaybackException If an error occurs.
+   */
+  /* package */ final void replaceTrackStream(Format[] formats, TrackStream trackStream)
+      throws ExoPlaybackException {
+    stream = trackStream;
+    onStreamChanged(formats);
+  }
+
+  /**
+   * Called when the renderer's stream has changed.
+   * <p>
+   * The default implementation is a no-op.
+   *
+   * @param formats The enabled formats.
+   * @throws ExoPlaybackException Thrown if an error occurs.
+   */
+  protected void onStreamChanged(Format[] formats) throws ExoPlaybackException {
     // Do nothing.
   }
 

library/src/main/java/com/google/android/exoplayer/extensions/AudioDecoderTrackRenderer.java

@@ -298,7 +298,7 @@ public abstract class AudioDecoderTrackRenderer extends TrackRenderer implements
   }
 
   @Override
-  protected void onEnabled(Format[] formats, boolean joining) throws ExoPlaybackException {
+  protected void onEnabled(boolean joining) throws ExoPlaybackException {
     codecCounters.reset();
     eventDispatcher.enabled(codecCounters);
   }

library/src/main/java/com/google/android/exoplayer/text/TextTrackRenderer.java

@@ -104,8 +104,10 @@ public final class TextTrackRenderer extends TrackRenderer implements Callback {
   }
 
   @Override
-  protected void onEnabled(Format[] formats, boolean joining) throws ExoPlaybackException {
-    super.onEnabled(formats, joining);
+  protected void onStreamChanged(Format[] formats) throws ExoPlaybackException {
+    if (parser != null) {
+      parser.release();
+    }
     parser = parserFactory.createParser(formats[0]);
   }