Misc cleanup

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=195552434

library/core/src/main/java/com/google/android/exoplayer2/offline/DownloaderConstructorHelper.java

@@ -49,14 +49,17 @@ public final class DownloaderConstructorHelper {
   /**
    * @param cache Cache instance to be used to store downloaded data.
    * @param upstreamDataSourceFactory A {@link Factory} for downloading data.
-   * @param cacheReadDataSourceFactory A {@link Factory} for reading data from the cache.
-   *     If null, null is passed to {@link Downloader} constructor.
+   * @param cacheReadDataSourceFactory A {@link Factory} for reading data from the cache. If null
+   *     then standard {@link FileDataSource} instances will be used.
    * @param cacheWriteDataSinkFactory A {@link DataSink.Factory} for writing data to the cache. If
-   *     null, null is passed to {@link Downloader} constructor.
-   * @param priorityTaskManager If one is given then the download priority is set lower than
-   *     loading. If null, null is passed to {@link Downloader} constructor.
+   *     null then standard {@link CacheDataSink} instances will be used.
+   * @param priorityTaskManager A {@link PriorityTaskManager} to use when downloading. If non-null,
+   *     downloaders will register as tasks with priority {@link C#PRIORITY_DOWNLOAD} whilst
+   *     downloading.
    */
-  public DownloaderConstructorHelper(Cache cache, Factory upstreamDataSourceFactory,
+  public DownloaderConstructorHelper(
+      Cache cache,
+      Factory upstreamDataSourceFactory,
       @Nullable Factory cacheReadDataSourceFactory,
       @Nullable DataSink.Factory cacheWriteDataSinkFactory,
       @Nullable PriorityTaskManager priorityTaskManager) {
@@ -73,7 +76,7 @@ public final class DownloaderConstructorHelper {
     return cache;
   }
 
-  /** Returns a {@link PriorityTaskManager} instance.*/
+  /** Returns a {@link PriorityTaskManager} instance. */
   public PriorityTaskManager getPriorityTaskManager() {
     // Return a dummy PriorityTaskManager if none is provided. Create a new PriorityTaskManager
     // each time so clients don't affect each other over the dummy PriorityTaskManager instance.

library/core/src/main/java/com/google/android/exoplayer2/offline/FilterableManifest.java

@@ -18,19 +18,20 @@ package com.google.android.exoplayer2.offline;
 import java.util.List;
 
 /**
- * A manifest that can generate copies of itself including only the tracks specified by the given
- * track keys.
+ * A manifest that can generate copies of itself including only the streams specified by the given
+ * keys.
  *
  * @param <T> The manifest type.
- * @param <K> The track key type.
+ * @param <K> The stream key type.
  */
 public interface FilterableManifest<T, K> {
 
   /**
-   * Returns a copy of the manifest including only the tracks specified by the given track keys.
+   * Returns a copy of the manifest including only the streams specified by the given keys. If the
+   * manifest is unchanged then the instance may return itself.
    *
-   * @param trackKeys A non-empty list of track keys.
+   * @param streamKeys A non-empty list of stream keys.
    * @return The filtered manifest.
    */
-  T copy(List<K> trackKeys);
+  T copy(List<K> streamKeys);
 }

library/core/src/main/java/com/google/android/exoplayer2/offline/SegmentDownloader.java

@@ -35,7 +35,7 @@ import java.util.concurrent.atomic.AtomicBoolean;
  * Base class for multi segment stream downloaders.
  *
  * @param <M> The type of the manifest object.
- * @param <K> The type of the track key object.
+ * @param <K> The type of the streams key object.
  */
 public abstract class SegmentDownloader<M extends FilterableManifest<M, K>, K>
     implements Downloader {
@@ -68,7 +68,7 @@ public abstract class SegmentDownloader<M extends FilterableManifest<M, K>, K>
   private final Cache cache;
   private final CacheDataSource dataSource;
   private final CacheDataSource offlineDataSource;
-  private final ArrayList<K> keys;
+  private final ArrayList<K> streamKeys;
   private final AtomicBoolean isCanceled;
 
   private volatile int totalSegments;
@@ -77,23 +77,24 @@ public abstract class SegmentDownloader<M extends FilterableManifest<M, K>, K>
 
   /**
    * @param manifestUri The {@link Uri} of the manifest to be downloaded.
+   * @param streamKeys Keys defining which streams in the manifest should be selected for download.
+   *     If empty, all streams are downloaded.
    * @param constructorHelper A {@link DownloaderConstructorHelper} instance.
-   * @param trackKeys Track keys to select when downloading. If empty, all tracks are downloaded.
    */
   public SegmentDownloader(
-      Uri manifestUri, DownloaderConstructorHelper constructorHelper, List<K> trackKeys) {
+      Uri manifestUri, List<K> streamKeys, DownloaderConstructorHelper constructorHelper) {
     this.manifestUri = manifestUri;
+    this.streamKeys = new ArrayList<>(streamKeys);
     this.cache = constructorHelper.getCache();
     this.dataSource = constructorHelper.buildCacheDataSource(false);
     this.offlineDataSource = constructorHelper.buildCacheDataSource(true);
     this.priorityTaskManager = constructorHelper.getPriorityTaskManager();
-    keys = new ArrayList<>(trackKeys);
     totalSegments = C.LENGTH_UNSET;
     isCanceled = new AtomicBoolean();
   }
 
   /**
-   * Downloads the selected tracks in the media. If multiple tracks are selected, they are
+   * Downloads the selected streams in the media. If multiple streams are selected, they are
    * downloaded in sync with one another.
    *
    * @throws IOException Thrown when there is an error downloading.
@@ -202,8 +203,8 @@ public abstract class SegmentDownloader<M extends FilterableManifest<M, K>, K>
   /** Initializes the download, returning a list of {@link Segment}s that need to be downloaded. */
   private List<Segment> initDownload() throws IOException, InterruptedException {
     M manifest = getManifest(dataSource, manifestUri);
-    if (!keys.isEmpty()) {
-      manifest = manifest.copy(keys);
+    if (!streamKeys.isEmpty()) {
+      manifest = manifest.copy(streamKeys);
     }
     List<Segment> segments = getSegments(dataSource, manifest, /* allowIncompleteList= */ false);
     CachingCounters cachingCounters = new CachingCounters();

library/core/src/main/java/com/google/android/exoplayer2/offline/TrackKey.java

@@ -19,10 +19,13 @@ package com.google.android.exoplayer2.offline;
  * Identifies a given track by the index of the containing period, the index of the containing group
  * within the period, and the index of the track within the group.
  */
-public class TrackKey {
+public final class TrackKey {
 
+  /** The period index. */
   public final int periodIndex;
+  /** The group index. */
   public final int groupIndex;
+  /** The track index. */
   public final int trackIndex;
 
   /**

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

@@ -122,17 +122,9 @@ public class DashManifest implements FilterableManifest<DashManifest, Representa
     return C.msToUs(getPeriodDurationMs(index));
   }
 
-  /**
-   * Creates a copy of this manifest which includes only the representations identified by the given
-   * keys.
-   *
-   * @param representationKeys List of keys for the representations to be included in the copy.
-   * @return A copy of this manifest with the selected representations.
-   * @throws IndexOutOfBoundsException If a key has an invalid index.
-   */
   @Override
-  public final DashManifest copy(List<RepresentationKey> representationKeys) {
-    LinkedList<RepresentationKey> keys = new LinkedList<>(representationKeys);
+  public final DashManifest copy(List<RepresentationKey> streamKeys) {
+    LinkedList<RepresentationKey> keys = new LinkedList<>(streamKeys);
     Collections.sort(keys);
     keys.add(new RepresentationKey(-1, -1, -1)); // Add a stopper key to the end
 

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

@@ -61,7 +61,7 @@ public final class DashDownloadAction extends SegmentDownloadAction<Representati
 
   @Override
   protected DashDownloader createDownloader(DownloaderConstructorHelper constructorHelper) {
-    return new DashDownloader(uri, constructorHelper, keys);
+    return new DashDownloader(uri, keys, constructorHelper);
   }
 
   @Override

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

@@ -52,8 +52,8 @@ import java.util.List;
  * DashDownloader dashDownloader =
  *     new DashDownloader(
  *         manifestUrl,
- *         constructorHelper,
- *         Collections.singletonList(new RepresentationKey(0, 0, 0)));
+ *         Collections.singletonList(new RepresentationKey(0, 0, 0)),
+ *         constructorHelper);
  * // Perform the download.
  * dashDownloader.download();
  * // Access downloaded data using CacheDataSource
@@ -63,12 +63,17 @@ import java.util.List;
  */
 public final class DashDownloader extends SegmentDownloader<DashManifest, RepresentationKey> {
 
-  /** @see SegmentDownloader#SegmentDownloader(Uri, DownloaderConstructorHelper, List) */
+  /**
+   * @param manifestUri The {@link Uri} of the manifest to be downloaded.
+   * @param representationKeys Keys defining which representations in the manifest should be
+   *     selected for download. If empty, all representations are downloaded.
+   * @param constructorHelper A {@link DownloaderConstructorHelper} instance.
+   */
   public DashDownloader(
       Uri manifestUri,
-      DownloaderConstructorHelper constructorHelper,
-      List<RepresentationKey> trackKeys) {
-    super(manifestUri, constructorHelper, trackKeys);
+      List<RepresentationKey> representationKeys,
+      DownloaderConstructorHelper constructorHelper) {
+    super(manifestUri, representationKeys, constructorHelper);
   }
 
   @Override

library/dash/src/test/java/com/google/android/exoplayer2/source/dash/offline/DashDownloaderTest.java

@@ -305,7 +305,7 @@ public class DashDownloaderTest {
 
   private DashDownloader getDashDownloader(Factory factory, RepresentationKey... keys) {
     return new DashDownloader(
-        TEST_MPD_URI, new DownloaderConstructorHelper(cache, factory), keysList(keys));
+        TEST_MPD_URI, keysList(keys), new DownloaderConstructorHelper(cache, factory));
   }
 
   private static ArrayList<RepresentationKey> keysList(RepresentationKey... keys) {

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

@@ -63,7 +63,7 @@ public final class HlsDownloadAction extends SegmentDownloadAction<RenditionKey>
 
   @Override
   protected HlsDownloader createDownloader(DownloaderConstructorHelper constructorHelper) {
-    return new HlsDownloader(uri, constructorHelper, keys);
+    return new HlsDownloader(uri, keys, constructorHelper);
   }
 
   @Override

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

@@ -43,7 +43,7 @@ public final class HlsDownloadHelper extends DownloadHelper {
   private final Uri uri;
   private final DataSource.Factory manifestDataSourceFactory;
 
-  private @MonotonicNonNull HlsPlaylist<?> playlist;
+  private @MonotonicNonNull HlsPlaylist playlist;
   private int[] renditionTypes;
 
   public HlsDownloadHelper(Uri uri, DataSource.Factory manifestDataSourceFactory) {

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

@@ -34,54 +34,76 @@ import java.util.ArrayList;
 import java.util.HashSet;
 import java.util.List;
 
-/** A downloader for HLS streams. */
-public final class HlsDownloader extends SegmentDownloader<HlsMasterPlaylist, RenditionKey> {
+/**
+ * A downloader for HLS streams.
+ *
+ * <p>Example usage:
+ *
+ * <pre>{@code
+ * SimpleCache cache = new SimpleCache(downloadFolder, new NoOpCacheEvictor());
+ * DefaultHttpDataSourceFactory factory = new DefaultHttpDataSourceFactory("ExoPlayer", null);
+ * DownloaderConstructorHelper constructorHelper =
+ *     new DownloaderConstructorHelper(cache, factory);
+ * // Create a downloader for the first variant in a master playlist.
+ * HlsDownloader hlsDownloader =
+ *     new HlsDownloader(
+ *         playlistUri,
+ *         Collections.singletonList(new RenditionKey(RenditionKey.TYPE_VARIANT, 0)),
+ *         constructorHelper);
+ * // Perform the download.
+ * hlsDownloader.download();
+ * // Access downloaded data using CacheDataSource
+ * CacheDataSource cacheDataSource =
+ *     new CacheDataSource(cache, factory.createDataSource(), CacheDataSource.FLAG_BLOCK_ON_CACHE);
+ * }</pre>
+ */
+public final class HlsDownloader extends SegmentDownloader<HlsPlaylist, RenditionKey> {
 
-  /** @see SegmentDownloader#SegmentDownloader(Uri, DownloaderConstructorHelper, List) */
+  /**
+   * @param playlistUri The {@link Uri} of the playlist to be downloaded.
+   * @param renditionKeys Keys defining which renditions in the playlist should be selected for
+   *     download. If empty, all renditions are downloaded.
+   * @param constructorHelper A {@link DownloaderConstructorHelper} instance.
+   */
   public HlsDownloader(
-      Uri manifestUri,
-      DownloaderConstructorHelper constructorHelper,
-      List<RenditionKey> trackKeys) {
-    super(manifestUri, constructorHelper, trackKeys);
+      Uri playlistUri,
+      List<RenditionKey> renditionKeys,
+      DownloaderConstructorHelper constructorHelper) {
+    super(playlistUri, renditionKeys, constructorHelper);
   }
 
   @Override
-  protected HlsMasterPlaylist getManifest(DataSource dataSource, Uri uri) throws IOException {
-    HlsPlaylist hlsPlaylist = loadManifest(dataSource, uri);
-    if (hlsPlaylist instanceof HlsMasterPlaylist) {
-      return (HlsMasterPlaylist) hlsPlaylist;
-    } else {
-      return HlsMasterPlaylist.createSingleVariantMasterPlaylist(hlsPlaylist.baseUri);
-    }
+  protected HlsPlaylist getManifest(DataSource dataSource, Uri uri) throws IOException {
+    return loadManifest(dataSource, uri);
   }
 
   @Override
   protected List<Segment> getSegments(
-      DataSource dataSource, HlsMasterPlaylist manifest, boolean allowIncompleteList)
-      throws IOException {
-    HashSet<Uri> encryptionKeyUris = new HashSet<>();
-    ArrayList<HlsUrl> renditionUrls = new ArrayList<>();
-    renditionUrls.addAll(manifest.variants);
-    renditionUrls.addAll(manifest.audios);
-    renditionUrls.addAll(manifest.subtitles);
+      DataSource dataSource, HlsPlaylist playlist, boolean allowIncompleteList) throws IOException {
+    ArrayList<Uri> mediaPlaylistUris = new ArrayList<>();
+    if (playlist instanceof HlsMasterPlaylist) {
+      HlsMasterPlaylist masterPlaylist = (HlsMasterPlaylist) playlist;
+      addResolvedUris(masterPlaylist.baseUri, masterPlaylist.variants, mediaPlaylistUris);
+      addResolvedUris(masterPlaylist.baseUri, masterPlaylist.audios, mediaPlaylistUris);
+      addResolvedUris(masterPlaylist.baseUri, masterPlaylist.subtitles, mediaPlaylistUris);
+    } else {
+      mediaPlaylistUris.add(Uri.parse(playlist.baseUri));
+    }
     ArrayList<Segment> segments = new ArrayList<>();
 
-    for (HlsUrl renditionUrl : renditionUrls) {
-      HlsMediaPlaylist mediaPlaylist = null;
-      Uri uri = UriUtil.resolveToUri(manifest.baseUri, renditionUrl.url);
+    HashSet<Uri> seenEncryptionKeyUris = new HashSet<>();
+    for (Uri mediaPlaylistUri : mediaPlaylistUris) {
+      HlsMediaPlaylist mediaPlaylist;
       try {
-        mediaPlaylist = (HlsMediaPlaylist) loadManifest(dataSource, uri);
+        mediaPlaylist = (HlsMediaPlaylist) loadManifest(dataSource, mediaPlaylistUri);
+        segments.add(new Segment(mediaPlaylist.startTimeUs, new DataSpec(mediaPlaylistUri)));
       } catch (IOException e) {
         if (!allowIncompleteList) {
           throw e;
         }
-      }
-      segments.add(new Segment(mediaPlaylist != null ? mediaPlaylist.startTimeUs : Long.MIN_VALUE,
-          new DataSpec(uri)));
-      if (mediaPlaylist == null) {
+        segments.add(new Segment(0, new DataSpec(mediaPlaylistUri)));
         continue;
       }
-
       HlsMediaPlaylist.Segment lastInitSegment = null;
       List<HlsMediaPlaylist.Segment> hlsSegments = mediaPlaylist.segments;
       for (int i = 0; i < hlsSegments.size(); i++) {
@@ -89,9 +111,9 @@ public final class HlsDownloader extends SegmentDownloader<HlsMasterPlaylist, Re
         HlsMediaPlaylist.Segment initSegment = segment.initializationSegment;
         if (initSegment != null && initSegment != lastInitSegment) {
           lastInitSegment = initSegment;
-          addSegment(segments, mediaPlaylist, initSegment, encryptionKeyUris);
+          addSegment(segments, mediaPlaylist, initSegment, seenEncryptionKeyUris);
         }
-        addSegment(segments, mediaPlaylist, segment, encryptionKeyUris);
+        addSegment(segments, mediaPlaylist, segment, seenEncryptionKeyUris);
       }
     }
     return segments;
@@ -108,12 +130,12 @@ public final class HlsDownloader extends SegmentDownloader<HlsMasterPlaylist, Re
       ArrayList<Segment> segments,
       HlsMediaPlaylist mediaPlaylist,
       HlsMediaPlaylist.Segment hlsSegment,
-      HashSet<Uri> encryptionKeyUris) {
+      HashSet<Uri> seenEncryptionKeyUris) {
     long startTimeUs = mediaPlaylist.startTimeUs + hlsSegment.relativeStartTimeUs;
     if (hlsSegment.fullSegmentEncryptionKeyUri != null) {
       Uri keyUri = UriUtil.resolveToUri(mediaPlaylist.baseUri,
           hlsSegment.fullSegmentEncryptionKeyUri);
-      if (encryptionKeyUris.add(keyUri)) {
+      if (seenEncryptionKeyUris.add(keyUri)) {
         segments.add(new Segment(startTimeUs, new DataSpec(keyUri)));
       }
     }
@@ -122,4 +144,9 @@ public final class HlsDownloader extends SegmentDownloader<HlsMasterPlaylist, Re
         new DataSpec(resolvedUri, hlsSegment.byterangeOffset, hlsSegment.byterangeLength, null)));
   }
 
+  private static void addResolvedUris(String baseUri, List<HlsUrl> urls, List<Uri> out) {
+    for (int i = 0; i < urls.size(); i++) {
+      out.add(UriUtil.resolveToUri(baseUri, urls.get(i).url));
+    }
+  }
 }

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

@@ -22,7 +22,7 @@ import java.util.Collections;
 import java.util.List;
 
 /** Represents an HLS master playlist. */
-public final class HlsMasterPlaylist extends HlsPlaylist<HlsMasterPlaylist> {
+public final class HlsMasterPlaylist extends HlsPlaylist {
 
   /**
    * Represents a url in an HLS master playlist.
@@ -107,14 +107,6 @@ public final class HlsMasterPlaylist extends HlsPlaylist<HlsMasterPlaylist> {
         ? Collections.unmodifiableList(muxedCaptionFormats) : null;
   }
 
-  /**
-   * Returns a copy of this playlist which includes only the renditions identified by the given
-   * keys.
-   *
-   * @param renditionKeys List of rendition keys.
-   * @return A copy of this playlist which includes only the renditions identified by the given
-   *     urls.
-   */
   @Override
   public HlsMasterPlaylist copy(List<RenditionKey> renditionKeys) {
     return new HlsMasterPlaylist(

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

@@ -26,7 +26,7 @@ import java.util.Collections;
 import java.util.List;
 
 /** Represents an HLS media playlist. */
-public final class HlsMediaPlaylist extends HlsPlaylist<HlsMediaPlaylist> {
+public final class HlsMediaPlaylist extends HlsPlaylist {
 
   /** Media segment reference. */
   @SuppressWarnings("ComparableType")

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

@@ -20,8 +20,7 @@ import java.util.Collections;
 import java.util.List;
 
 /** Represents an HLS playlist. */
-public abstract class HlsPlaylist<T extends HlsPlaylist<T>>
-    implements FilterableManifest<T, RenditionKey> {
+public abstract class HlsPlaylist implements FilterableManifest<HlsPlaylist, RenditionKey> {
 
   /**
    * The base uri. Used to resolve relative paths.

library/hls/src/test/java/com/google/android/exoplayer2/source/hls/offline/HlsDownloaderTest.java

@@ -184,7 +184,7 @@ public class HlsDownloaderTest {
   private HlsDownloader getHlsDownloader(String mediaPlaylistUri, List<RenditionKey> keys) {
     Factory factory = new Factory(null).setFakeDataSet(fakeDataSet);
     return new HlsDownloader(
-        Uri.parse(mediaPlaylistUri), new DownloaderConstructorHelper(cache, factory), keys);
+        Uri.parse(mediaPlaylistUri), keys, new DownloaderConstructorHelper(cache, factory));
   }
 
   private static ArrayList<RenditionKey> getKeys(int... variantIndices) {

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

@@ -120,16 +120,9 @@ public class SsManifest implements FilterableManifest<SsManifest, StreamKey> {
     this.streamElements = streamElements;
   }
 
-  /**
-   * Creates a copy of this manifest which includes only the tracks identified by the given keys.
-   *
-   * @param trackKeys List of keys for the tracks to be included in the copy.
-   * @return A copy of this manifest with the selected tracks.
-   * @throws IndexOutOfBoundsException If a key has an invalid index.
-   */
   @Override
-  public final SsManifest copy(List<StreamKey> trackKeys) {
-    ArrayList<StreamKey> sortedKeys = new ArrayList<>(trackKeys);
+  public final SsManifest copy(List<StreamKey> streamKeys) {
+    ArrayList<StreamKey> sortedKeys = new ArrayList<>(streamKeys);
     Collections.sort(sortedKeys);
 
     StreamElement currentStreamElement = null;

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

@@ -51,7 +51,7 @@ public final class SsDownloadAction extends SegmentDownloadAction<StreamKey> {
    * @param uri The SmoothStreaming manifest URI.
    * @param isRemoveAction Whether the data will be removed. If {@code false} it will be downloaded.
    * @param data Optional custom data for this action.
-   * @param keys Keys of tracks to be downloaded. If empty, all tracks are downloaded. If {@code
+   * @param keys Keys of streams to be downloaded. If empty, all streams are downloaded. If {@code
    *     removeAction} is true, {@code keys} must be empty.
    */
   public SsDownloadAction(
@@ -61,7 +61,7 @@ public final class SsDownloadAction extends SegmentDownloadAction<StreamKey> {
 
   @Override
   protected SsDownloader createDownloader(DownloaderConstructorHelper constructorHelper) {
-    return new SsDownloader(uri, constructorHelper, keys);
+    return new SsDownloader(uri, keys, constructorHelper);
   }
 
   @Override

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

@@ -45,8 +45,8 @@ import java.util.List;
  * SsDownloader ssDownloader =
  *     new SsDownloader(
  *         manifestUrl,
- *         constructorHelper,
- *         Collections.singletonList(new StreamKey(0, 0)));
+ *         Collections.singletonList(new StreamKey(0, 0)),
+ *         constructorHelper);
  * // Perform the download.
  * ssDownloader.download();
  * // Access downloaded data using CacheDataSource
@@ -56,10 +56,15 @@ import java.util.List;
  */
 public final class SsDownloader extends SegmentDownloader<SsManifest, StreamKey> {
 
-  /** @see SegmentDownloader#SegmentDownloader(Uri, DownloaderConstructorHelper, List) */
+  /**
+   * @param manifestUri The {@link Uri} of the manifest to be downloaded.
+   * @param streamKeys Keys defining which streams in the manifest should be selected for download.
+   *     If empty, all streams are downloaded.
+   * @param constructorHelper A {@link DownloaderConstructorHelper} instance.
+   */
   public SsDownloader(
-      Uri manifestUri, DownloaderConstructorHelper constructorHelper, List<StreamKey> trackKeys) {
-    super(SsUtil.fixManifestUri(manifestUri), constructorHelper, trackKeys);
+      Uri manifestUri, List<StreamKey> streamKeys, DownloaderConstructorHelper constructorHelper) {
+    super(SsUtil.fixManifestUri(manifestUri), streamKeys, constructorHelper);
   }
 
   @Override

playbacktests/src/androidTest/java/com/google/android/exoplayer2/playbacktests/gts/DashDownloadTest.java

@@ -123,7 +123,7 @@ public final class DashDownloadTest extends ActivityInstrumentationTestCase2<Hos
     }
     DownloaderConstructorHelper constructorHelper =
         new DownloaderConstructorHelper(cache, httpDataSourceFactory);
-    return new DashDownloader(MANIFEST_URI, constructorHelper, keys);
+    return new DashDownloader(MANIFEST_URI, keys, constructorHelper);
   }
 
 }