Check the type of the (non-initial) loaded HLS playlist

This prevents illegal casts.

Issue:#2702

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=154078240

library/hls/src/androidTest/java/com/google/android/exoplayer2/source/hls/playlist/HlsMediaPlaylistParserTest.java

@@ -70,7 +70,6 @@ public class HlsMediaPlaylistParserTest extends TestCase {
     try {
     try {
       HlsPlaylist playlist = new HlsPlaylistParser().parse(playlistUri, inputStream);
       HlsPlaylist playlist = new HlsPlaylistParser().parse(playlistUri, inputStream);
       assertNotNull(playlist);
       assertNotNull(playlist);
-      assertEquals(HlsPlaylist.TYPE_MEDIA, playlist.type);
 
 
       HlsMediaPlaylist mediaPlaylist = (HlsMediaPlaylist) playlist;
       HlsMediaPlaylist mediaPlaylist = (HlsMediaPlaylist) playlist;
       assertEquals(HlsMediaPlaylist.PLAYLIST_TYPE_VOD, mediaPlaylist.playlistType);
       assertEquals(HlsMediaPlaylist.PLAYLIST_TYPE_VOD, mediaPlaylist.playlistType);

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

@@ -55,7 +55,7 @@ public final class HlsMasterPlaylist extends HlsPlaylist {
 
 
   public HlsMasterPlaylist(String baseUri, List<HlsUrl> variants, List<HlsUrl> audios,
   public HlsMasterPlaylist(String baseUri, List<HlsUrl> variants, List<HlsUrl> audios,
       List<HlsUrl> subtitles, Format muxedAudioFormat, List<Format> muxedCaptionFormats) {
       List<HlsUrl> subtitles, Format muxedAudioFormat, List<Format> muxedCaptionFormats) {
-    super(baseUri, HlsPlaylist.TYPE_MASTER);
+    super(baseUri);
     this.variants = Collections.unmodifiableList(variants);
     this.variants = Collections.unmodifiableList(variants);
     this.audios = Collections.unmodifiableList(audios);
     this.audios = Collections.unmodifiableList(audios);
     this.subtitles = Collections.unmodifiableList(subtitles);
     this.subtitles = Collections.unmodifiableList(subtitles);

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

@@ -97,7 +97,7 @@ public final class HlsMediaPlaylist extends HlsPlaylist {
       long startTimeUs, boolean hasDiscontinuitySequence, int discontinuitySequence,
       long startTimeUs, boolean hasDiscontinuitySequence, int discontinuitySequence,
       int mediaSequence, int version, long targetDurationUs, boolean hasEndTag,
       int mediaSequence, int version, long targetDurationUs, boolean hasEndTag,
       boolean hasProgramDateTime, Segment initializationSegment, List<Segment> segments) {
       boolean hasProgramDateTime, Segment initializationSegment, List<Segment> segments) {
-    super(baseUri, HlsPlaylist.TYPE_MEDIA);
+    super(baseUri);
     this.playlistType = playlistType;
     this.playlistType = playlistType;
     this.startTimeUs = startTimeUs;
     this.startTimeUs = startTimeUs;
     this.hasDiscontinuitySequence = hasDiscontinuitySequence;
     this.hasDiscontinuitySequence = hasDiscontinuitySequence;

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

@@ -15,30 +15,15 @@
  */
  */
 package com.google.android.exoplayer2.source.hls.playlist;
 package com.google.android.exoplayer2.source.hls.playlist;
 
 
-import android.support.annotation.IntDef;
-import java.lang.annotation.Retention;
-import java.lang.annotation.RetentionPolicy;
-
 /**
 /**
  * Represents an HLS playlist.
  * Represents an HLS playlist.
  */
  */
 public abstract class HlsPlaylist {
 public abstract class HlsPlaylist {
 
 
-  /**
-   * The type of playlist.
-   */
-  @Retention(RetentionPolicy.SOURCE)
-  @IntDef({TYPE_MASTER, TYPE_MEDIA})
-  public @interface Type {}
-  public static final int TYPE_MASTER = 0;
-  public static final int TYPE_MEDIA = 1;
-
   public final String baseUri;
   public final String baseUri;
-  @Type public final int type;
 
 
-  protected HlsPlaylist(String baseUri, @Type int type) {
+  protected HlsPlaylist(String baseUri) {
     this.baseUri = baseUri;
     this.baseUri = baseUri;
-    this.type = type;
   }
   }
 
 
 }
 }

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

@@ -477,9 +477,15 @@ public final class HlsPlaylistTracker implements Loader.Callback<ParsingLoadable
     @Override
     @Override
     public void onLoadCompleted(ParsingLoadable<HlsPlaylist> loadable, long elapsedRealtimeMs,
     public void onLoadCompleted(ParsingLoadable<HlsPlaylist> loadable, long elapsedRealtimeMs,
         long loadDurationMs) {
         long loadDurationMs) {
-      processLoadedPlaylist((HlsMediaPlaylist) loadable.getResult());
-      eventDispatcher.loadCompleted(loadable.dataSpec, C.DATA_TYPE_MANIFEST, elapsedRealtimeMs,
-          loadDurationMs, loadable.bytesLoaded());
+      HlsPlaylist result = loadable.getResult();
+      if (result instanceof HlsMediaPlaylist) {
+        processLoadedPlaylist((HlsMediaPlaylist) result);
+        eventDispatcher.loadCompleted(loadable.dataSpec, C.DATA_TYPE_MANIFEST, elapsedRealtimeMs,
+            loadDurationMs, loadable.bytesLoaded());
+      } else {
+        onLoadError(loadable, elapsedRealtimeMs, loadDurationMs,
+            new ParserException("Loaded playlist has unexpected type."));
+      }
     }
     }
 
 
     @Override
     @Override