Fix HLS track selection.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=123851448

library/src/main/java/com/google/android/exoplayer/hls/HlsChunkSource.java

@@ -112,7 +112,7 @@ public class HlsChunkSource {
     evaluation = new Evaluation();
     variantPlaylists = new HlsMediaPlaylist[variants.length];
     variantLastPlaylistLoadTimesMs = new long[variants.length];
-    selectTracks(new int[] {0});
+    selectTracks(new int[] {0}, false);
   }
 
   /**
@@ -187,11 +187,9 @@ public class HlsChunkSource {
    * This method should only be called after the source has been prepared.
    *
    * @param tracks The track indices.
-   * @return True if one or more tracks was unselected. False otherwise.
+   * @param isFirstTrackSelection True if this is the first selection, false otherwise.
    */
-  public boolean selectTracks(int[] tracks) {
-    Variant[] oldEnabledVariants = enabledVariants;
-
+  public void selectTracks(int[] tracks, boolean isFirstTrackSelection) {
     // Construct and sort the enabled variants.
     enabledVariants = new Variant[tracks.length];
     for (int i = 0; i < tracks.length; i++) {
@@ -217,16 +215,10 @@ public class HlsChunkSource {
       }
       // TODO[REFACTOR]: We need to disable this at some point.
       adaptiveFormatEvaluator.enable(formats);
-    }
-
-    if (oldEnabledVariants != null) {
-      for (Variant oldVariant : oldEnabledVariants) {
-        if (!Util.contains(enabledVariants, oldVariant)) {
-          return true;
-        }
+      if (!isFirstTrackSelection || !Util.contains(formats, evaluation.format)) {
+        evaluation.format = null;
       }
     }
-    return false;
   }
 
   /**

library/src/main/java/com/google/android/exoplayer/hls/HlsSampleSource.java

@@ -163,7 +163,7 @@ public final class HlsSampleSource implements SampleSource,
     int enabledTrackStreamWrapperCount = 0;
     for (int i = 0; i < trackStreamWrappers.length; i++) {
       selectedTrackCounts[i] += selectTracks(trackStreamWrappers[i], oldStreams, newSelections,
-          positionUs, newStreams);
+          newStreams);
       if (selectedTrackCounts[i] > 0) {
         enabledTrackStreamWrapperCount++;
       }
@@ -176,6 +176,9 @@ public final class HlsSampleSource implements SampleSource,
         enabledTrackStreamWrappers[enabledTrackStreamWrapperCount++] = trackStreamWrappers[i];
       }
     }
+    if (enabledTrackStreamWrapperCount > 0 && seenFirstTrackSelection && !newSelections.isEmpty()) {
+      seekToUs(positionUs);
+    }
     seenFirstTrackSelection = true;
     return newStreams;
   }
@@ -220,7 +223,7 @@ public final class HlsSampleSource implements SampleSource,
     timestampAdjusterProvider.reset();
     for (HlsTrackStreamWrapper trackStreamWrapper : enabledTrackStreamWrappers) {
       trackStreamWrapper.setReadingEnabled(false);
-      trackStreamWrapper.seekToUs(positionUs);
+      trackStreamWrapper.restartFrom(positionUs);
     }
   }
 
@@ -335,7 +338,7 @@ public final class HlsSampleSource implements SampleSource,
   }
 
   private int selectTracks(HlsTrackStreamWrapper trackStreamWrapper,
-      List<TrackStream> allOldStreams, List<TrackSelection> allNewSelections, long positionUs,
+      List<TrackStream> allOldStreams, List<TrackSelection> allNewSelections,
       TrackStream[] allNewStreams) {
     // Get the subset of the old streams for the source.
     ArrayList<TrackStream> oldStreams = new ArrayList<>();
@@ -363,7 +366,7 @@ public final class HlsSampleSource implements SampleSource,
     }
     // Perform the selection.
     TrackStream[] newStreams = trackStreamWrapper.selectTracks(oldStreams, newSelections,
-        positionUs);
+        !seenFirstTrackSelection);
     for (int j = 0; j < newStreams.length; j++) {
       allNewStreams[newSelectionOriginalIndices[j]] = newStreams[j];
       trackStreamSources.put(newStreams[j], trackStreamWrapper);

library/src/main/java/com/google/android/exoplayer/hls/HlsTrackStreamWrapper.java

@@ -69,7 +69,6 @@ import java.util.List;
   private volatile boolean sampleQueuesBuilt;
 
   private boolean prepared;
-  private boolean seenFirstTrackSelection;
   private boolean readingEnabled;
   private int enabledTrackCount;
   private Format downstreamFormat;
@@ -171,7 +170,7 @@ import java.util.List;
   }
 
   public TrackStream[] selectTracks(List<TrackStream> oldStreams,
-      List<TrackSelection> newSelections, long positionUs) {
+      List<TrackSelection> newSelections, boolean isFirstTrackSelection) {
     Assertions.checkState(prepared);
     boolean tracksWereEnabled = enabledTrackCount > 0;
     // Unselect old tracks.
@@ -180,7 +179,6 @@ import java.util.List;
       setTrackGroupEnabledState(group, false);
     }
     // Select new tracks.
-    boolean primaryTracksDeselected = false;
     TrackStream[] newStreams = new TrackStream[newSelections.size()];
     for (int i = 0; i < newStreams.length; i++) {
       TrackSelection selection = newSelections.get(i);
@@ -189,7 +187,7 @@ import java.util.List;
       setTrackGroupEnabledState(group, true);
       sampleQueues.valueAt(group).needDownstreamFormat();
       if (group == primaryTrackGroupIndex) {
-        primaryTracksDeselected |= chunkSource.selectTracks(tracks);
+        chunkSource.selectTracks(tracks, isFirstTrackSelection);
       }
       newStreams[i] = new TrackStreamImpl(group);
     }
@@ -207,15 +205,9 @@ import java.util.List;
         clearState();
         loadControl.trimAllocator();
       }
-    } else {
-      if (!tracksWereEnabled) {
-        loadControl.register(this, bufferSizeContribution);
-      }
-      if (primaryTracksDeselected || (seenFirstTrackSelection && newStreams.length > 0)) {
-        seekToInternal(positionUs);
-      }
+    } else if (!tracksWereEnabled) {
+      loadControl.register(this, bufferSizeContribution);
     }
-    seenFirstTrackSelection = true;
     return newStreams;
   }
 
@@ -253,8 +245,17 @@ import java.util.List;
     }
   }
 
-  public void seekToUs(long positionUs) {
-    seekToInternal(positionUs);
+  public void restartFrom(long positionUs) {
+    lastSeekPositionUs = positionUs;
+    downstreamPositionUs = positionUs;
+    pendingResetPositionUs = positionUs;
+    loadingFinished = false;
+    if (loader.isLoading()) {
+      loader.cancelLoading();
+    } else {
+      clearState();
+      maybeStartLoading();
+    }
   }
 
   public void release() {
@@ -500,17 +501,6 @@ import java.util.List;
         containerFormat.width, containerFormat.height, 0, containerFormat.language);
   }
 
-  /**
-   * Performs a seek. The operation is performed even if the seek is to the current position.
-   *
-   * @param positionUs The position to seek to.
-   */
-  private void seekToInternal(long positionUs) {
-    lastSeekPositionUs = positionUs;
-    downstreamPositionUs = positionUs;
-    restartFrom(positionUs);
-  }
-
   private void discardSamplesForDisabledTracks() {
     if (!prepared) {
       return;
@@ -522,17 +512,6 @@ import java.util.List;
     }
   }
 
-  private void restartFrom(long positionUs) {
-    pendingResetPositionUs = positionUs;
-    loadingFinished = false;
-    if (loader.isLoading()) {
-      loader.cancelLoading();
-    } else {
-      clearState();
-      maybeStartLoading();
-    }
-  }
-
   private void clearState() {
     for (int i = 0; i < sampleQueues.size(); i++) {
       sampleQueues.valueAt(i).clear();