Remove playlist adjustment on chunk loads

This is particularly problematic for subtitle tracks where adjustment
can be broken. Now, the primary url can change when clients ask for a
variant snapshot, instead of happening on chunk load as before.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=141933689

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

@@ -190,7 +190,7 @@ import java.util.Locale;
     // Use start time of the previous chunk rather than its end time because switching format will
     // require downloading overlapping segments.
     long bufferedDurationUs = previous == null ? 0
-        : Math.max(0, previous.getAdjustedStartTimeUs() - playbackPositionUs);
+        : Math.max(0, previous.startTimeUs - playbackPositionUs);
 
     // Select the variant.
     trackSelection.updateSelectedTrack(bufferedDurationUs);
@@ -291,11 +291,7 @@ import java.util.Locale;
    * @param chunk The chunk whose load has been completed.
    */
   public void onChunkLoadCompleted(Chunk chunk) {
-    if (chunk instanceof HlsMediaChunk) {
-      HlsMediaChunk mediaChunk = (HlsMediaChunk) chunk;
-      playlistTracker.onChunkLoaded(mediaChunk.hlsUrl, mediaChunk.chunkIndex,
-          mediaChunk.getAdjustedStartTimeUs());
-    } else if (chunk instanceof EncryptionKeyChunk) {
+    if (chunk instanceof EncryptionKeyChunk) {
       EncryptionKeyChunk encryptionKeyChunk = (EncryptionKeyChunk) chunk;
       scratchSpace = encryptionKeyChunk.getDataHolder();
       setEncryptionData(encryptionKeyChunk.dataSpec.uri, encryptionKeyChunk.iv,

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

@@ -91,7 +91,6 @@ import java.util.concurrent.atomic.AtomicInteger;
   private int bytesLoaded;
   private boolean initLoadCompleted;
   private HlsSampleStreamWrapper extractorOutput;
-  private long adjustedEndTimeUs;
   private volatile boolean loadCanceled;
   private volatile boolean loadCompleted;
 
@@ -141,7 +140,6 @@ import java.util.concurrent.atomic.AtomicInteger;
       id3Data = null;
     }
     initDataSource = dataSource;
-    adjustedEndTimeUs = endTimeUs;
     uid = UID_SOURCE.getAndIncrement();
   }
 
@@ -156,20 +154,6 @@ import java.util.concurrent.atomic.AtomicInteger;
     output.init(uid, previousChunk != null && previousChunk.hlsUrl != hlsUrl);
   }
 
-  /**
-   * Returns the presentation time in microseconds of the first sample in the chunk.
-   */
-  public long getAdjustedStartTimeUs() {
-    return adjustedEndTimeUs - getDurationUs();
-  }
-
-  /**
-   * Returns the presentation time in microseconds of the last sample in the chunk.
-   */
-  public long getAdjustedEndTimeUs() {
-    return adjustedEndTimeUs;
-  }
-
   @Override
   public boolean isLoadCompleted() {
     return loadCompleted;
@@ -265,10 +249,6 @@ import java.util.concurrent.atomic.AtomicInteger;
         while (result == Extractor.RESULT_CONTINUE && !loadCanceled) {
           result = extractor.read(input, null);
         }
-        long adjustedEndTimeUs = extractorOutput.getLargestQueuedTimestampUs();
-        if (adjustedEndTimeUs != Long.MIN_VALUE) {
-          this.adjustedEndTimeUs = adjustedEndTimeUs;
-        }
       } finally {
         bytesLoaded = (int) (input.getPosition() - dataSpec.absoluteStreamPosition);
       }

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

@@ -74,12 +74,6 @@ public final class HlsPlaylistTracker implements Loader.Callback<ParsingLoadable
 
   }
 
-  /**
-   * The minimum number of milliseconds by which a media playlist segment's start time has to drift
-   * from the actual start time of the chunk it refers to for it to be adjusted.
-   */
-  private static final long TIMESTAMP_ADJUSTMENT_THRESHOLD_US = 500000;
-
   /**
    * The minimum number of milliseconds that a url is kept as primary url, if no
    * {@link #getPlaylistSnapshot} call is made for that url.
@@ -172,6 +166,7 @@ public final class HlsPlaylistTracker implements Loader.Callback<ParsingLoadable
    *     be null if no snapshot has been loaded yet.
    */
   public HlsMediaPlaylist getPlaylistSnapshot(HlsUrl url) {
+    maybeSetPrimaryUrl(url);
     return playlistBundles.get(url).getPlaylistSnapshot();
   }
 
@@ -218,18 +213,6 @@ public final class HlsPlaylistTracker implements Loader.Callback<ParsingLoadable
     return isLive;
   }
 
-  /**
-   * Called when a chunk from a media playlist is loaded.
-   *
-   * @param hlsUrl The url of the playlist from which the chunk was obtained.
-   * @param chunkMediaSequence The media sequence number of the loaded chunk.
-   * @param adjustedStartTimeUs The adjusted start time of the loaded chunk.
-   */
-  public void onChunkLoaded(HlsUrl hlsUrl, int chunkMediaSequence, long adjustedStartTimeUs) {
-    playlistBundles.get(hlsUrl).adjustTimestampsOfPlaylist(chunkMediaSequence, adjustedStartTimeUs);
-    maybeSetPrimaryUrl(hlsUrl);
-  }
-
   // Loader.Callback implementation.
 
   @Override
@@ -295,8 +278,10 @@ public final class HlsPlaylistTracker implements Loader.Callback<ParsingLoadable
   }
 
   private void maybeSetPrimaryUrl(HlsUrl url) {
-    if (!masterPlaylist.variants.contains(url)) {
-      // Only allow variant urls to be chosen as primary.
+    if (!masterPlaylist.variants.contains(url)
+        || (primaryUrlSnapshot != null && primaryUrlSnapshot.hasEndTag)) {
+      // Only allow variant urls to be chosen as primary. Also prevent changing the primary url if
+      // the last primary snapshot contains an end tag.
       return;
     }
     MediaPlaylistBundle currentPrimaryBundle = playlistBundles.get(primaryHlsUrl);
@@ -429,22 +414,6 @@ public final class HlsPlaylistTracker implements Loader.Callback<ParsingLoadable
       }
     }
 
-    public void adjustTimestampsOfPlaylist(int chunkMediaSequence, long adjustedChunkStartTimeUs) {
-      int indexOfChunk = chunkMediaSequence - playlistSnapshot.mediaSequence;
-      if (playlistSnapshot.hasProgramDateTime || indexOfChunk < 0) {
-        return;
-      }
-      Segment actualSegment = playlistSnapshot.segments.get(indexOfChunk);
-      long segmentAbsoluteStartTimeUs =
-          actualSegment.relativeStartTimeUs + playlistSnapshot.startTimeUs;
-      long timestampDriftUs = Math.abs(segmentAbsoluteStartTimeUs - adjustedChunkStartTimeUs);
-      if (timestampDriftUs < TIMESTAMP_ADJUSTMENT_THRESHOLD_US) {
-        return;
-      }
-      playlistSnapshot = playlistSnapshot.copyWithStartTimeUs(
-          adjustedChunkStartTimeUs - actualSegment.relativeStartTimeUs);
-    }
-
     // Loader.Callback implementation.
 
     @Override