Add support for HLS track selection flags

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=125658752

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

@@ -60,6 +60,11 @@ public final class Format implements Parcelable {
    * Indicates that the track must be displayed. Only applies to text tracks.
    */
   public static final int SELECTION_FLAG_FORCED = 2;
+  /**
+   * Indicates that the player may choose to play the track in absence of an explicit user
+   * preference.
+   */
+  public static final int SELECTION_FLAG_AUTOSELECT = 4;
 
   /**
    * A value for {@link #subsampleOffsetUs} to indicate that subsample timestamps are relative to
@@ -391,6 +396,7 @@ public final class Format implements Parcelable {
     String codecs = this.codecs == null ? manifestFormat.codecs : this.codecs;
     int bitrate = this.bitrate == NO_VALUE ? manifestFormat.bitrate : this.bitrate;
     float frameRate = this.frameRate == NO_VALUE ? manifestFormat.frameRate : this.frameRate;
+    int selectionFlags = this.selectionFlags |  manifestFormat.selectionFlags;
     String language = this.language == null ? manifestFormat.language : this.language;
     DrmInitData drmInitData = (preferManifestDrmInitData && manifestFormat.drmInitData != null)
         || this.drmInitData == null ? manifestFormat.drmInitData : this.drmInitData;

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

@@ -510,7 +510,8 @@ import java.util.List;
       return sampleFormat;
     }
     return sampleFormat.copyWithContainerInfo(containerFormat.id, containerFormat.bitrate,
-        containerFormat.width, containerFormat.height, 0, containerFormat.language);
+        containerFormat.width, containerFormat.height, containerFormat.selectionFlags,
+        containerFormat.language);
   }
 
   private void maybeStartLoading() {

library/src/main/java/com/google/android/exoplayer/hls/playlist/HlsParserUtil.java

@@ -25,6 +25,9 @@ import java.util.regex.Pattern;
  */
 /* package */ final class HlsParserUtil {
 
+  private static final String BOOLEAN_TRUE_VALUE = "YES";
+  private static final String BOOLEAN_FALSE_VALUE = "NO";
+
   private HlsParserUtil() {}
 
   public static String parseStringAttr(String line, Pattern pattern, String tag)
@@ -54,4 +57,17 @@ import java.util.regex.Pattern;
     return null;
   }
 
+  public static boolean parseBooleanAttribute(String line, Pattern pattern, boolean defaultValue) {
+    Matcher matcher = pattern.matcher(line);
+    if (matcher.find()) {
+      return matcher.group(1).equals(BOOLEAN_TRUE_VALUE);
+    }
+    return defaultValue;
+  }
+
+  public static Pattern compileBooleanAttrPattern(String attribute) {
+    return Pattern.compile(attribute + "=(" + BOOLEAN_FALSE_VALUE + "|" + BOOLEAN_TRUE_VALUE + ")");
+
+  }
+
 }

library/src/main/java/com/google/android/exoplayer/hls/playlist/HlsPlaylistParser.java

@@ -62,6 +62,9 @@ public final class HlsPlaylistParser implements ParsingLoadable.Parser<HlsPlayli
   private static final String URI_ATTR = "URI";
   private static final String IV_ATTR = "IV";
   private static final String INSTREAM_ID_ATTR = "INSTREAM-ID";
+  private static final String AUTOSELECT_ATTR = "AUTOSELECT";
+  private static final String DEFAULT_ATTR = "DEFAULT";
+  private static final String FORCED_ATTR = "FORCED";
 
   private static final String AUDIO_TYPE = "AUDIO";
   private static final String VIDEO_TYPE = "VIDEO";
@@ -103,10 +106,12 @@ public final class HlsPlaylistParser implements ParsingLoadable.Parser<HlsPlayli
       Pattern.compile(NAME_ATTR + "=\"(.+?)\"");
   private static final Pattern INSTREAM_ID_ATTR_REGEX =
       Pattern.compile(INSTREAM_ID_ATTR + "=\"(.+?)\"");
-  // private static final Pattern AUTOSELECT_ATTR_REGEX =
-  //     HlsParserUtil.compileBooleanAttrPattern(AUTOSELECT_ATTR);
-  // private static final Pattern DEFAULT_ATTR_REGEX =
-  //     HlsParserUtil.compileBooleanAttrPattern(DEFAULT_ATTR);
+  private static final Pattern AUTOSELECT_ATTR_REGEX =
+      HlsParserUtil.compileBooleanAttrPattern(AUTOSELECT_ATTR);
+  private static final Pattern DEFAULT_ATTR_REGEX =
+      HlsParserUtil.compileBooleanAttrPattern(DEFAULT_ATTR);
+  private static final Pattern FORCED_ATTR_REGEX =
+      HlsParserUtil.compileBooleanAttrPattern(FORCED_ATTR);
 
   @Override
   public HlsPlaylist parse(Uri uri, InputStream inputStream) throws IOException {
@@ -159,6 +164,13 @@ public final class HlsPlaylistParser implements ParsingLoadable.Parser<HlsPlayli
     while (iterator.hasNext()) {
       line = iterator.next();
       if (line.startsWith(MEDIA_TAG)) {
+        boolean isDefault = HlsParserUtil.parseBooleanAttribute(line, DEFAULT_ATTR_REGEX, false);
+        boolean isForced = HlsParserUtil.parseBooleanAttribute(line, FORCED_ATTR_REGEX, false);
+        boolean isAutoselect = HlsParserUtil.parseBooleanAttribute(line, AUTOSELECT_ATTR_REGEX,
+            false);
+        int selectionFlags = (isDefault ? Format.SELECTION_FLAG_DEFAULT : 0)
+            | (isForced ? Format.SELECTION_FLAG_FORCED : 0)
+            | (isAutoselect ? Format.SELECTION_FLAG_AUTOSELECT : 0);
         String type = HlsParserUtil.parseStringAttr(line, TYPE_ATTR_REGEX, TYPE_ATTR);
         if (CLOSED_CAPTIONS_TYPE.equals(type)) {
           String instreamId = HlsParserUtil.parseStringAttr(line, INSTREAM_ID_ATTR_REGEX,
@@ -168,7 +180,8 @@ public final class HlsPlaylistParser implements ParsingLoadable.Parser<HlsPlayli
             String captionName = HlsParserUtil.parseStringAttr(line, NAME_ATTR_REGEX, NAME_ATTR);
             String language = HlsParserUtil.parseOptionalStringAttr(line, LANGUAGE_ATTR_REGEX);
             muxedCaptionFormat = Format.createTextContainerFormat(captionName,
-                MimeTypes.APPLICATION_M3U8, MimeTypes.APPLICATION_EIA608, null, -1, 0, language);
+                MimeTypes.APPLICATION_M3U8, MimeTypes.APPLICATION_EIA608, null, -1, selectionFlags,
+                language);
           }
         } else if (SUBTITLES_TYPE.equals(type)) {
           // We assume all subtitles belong to the same group.
@@ -176,7 +189,7 @@ public final class HlsPlaylistParser implements ParsingLoadable.Parser<HlsPlayli
           String uri = HlsParserUtil.parseStringAttr(line, URI_ATTR_REGEX, URI_ATTR);
           String language = HlsParserUtil.parseOptionalStringAttr(line, LANGUAGE_ATTR_REGEX);
           Format format = Format.createTextContainerFormat(subtitleName, MimeTypes.APPLICATION_M3U8,
-              MimeTypes.TEXT_VTT, null, bitrate, 0, language);
+              MimeTypes.TEXT_VTT, null, bitrate, selectionFlags, language);
           subtitles.add(new Variant(uri, format, codecs));
         } else if (AUDIO_TYPE.equals(type)) {
           // We assume all audios belong to the same group.
@@ -185,7 +198,7 @@ public final class HlsPlaylistParser implements ParsingLoadable.Parser<HlsPlayli
           String audioName = HlsParserUtil.parseStringAttr(line, NAME_ATTR_REGEX, NAME_ATTR);
           int audioBitrate = uri != null ? bitrate : -1;
           Format format = Format.createAudioContainerFormat(audioName, MimeTypes.APPLICATION_M3U8,
-              null, null, audioBitrate, -1, -1, null, 0, language);
+              null, null, audioBitrate, -1, -1, null, selectionFlags, language);
           if (uri != null) {
             audios.add(new Variant(uri, format, codecs));
           } else {