Added FLAC to the Webm list of known types.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=117226935

library/src/main/java/com/google/android/exoplayer/extractor/webm/WebmExtractor.java

@@ -80,6 +80,7 @@ public final class WebmExtractor implements Extractor {
   private static final String CODEC_ID_DTS = "A_DTS";
   private static final String CODEC_ID_DTS_EXPRESS = "A_DTS/EXPRESS";
   private static final String CODEC_ID_DTS_LOSSLESS = "A_DTS/LOSSLESS";
+  private static final String CODEC_ID_FLAC = "A_FLAC";
   private static final String CODEC_ID_SUBRIP = "S_TEXT/UTF8";
 
   private static final int VORBIS_MAX_INPUT_SIZE = 8192;
@@ -1051,6 +1052,7 @@ public final class WebmExtractor implements Extractor {
         || CODEC_ID_DTS.equals(codecId)
         || CODEC_ID_DTS_EXPRESS.equals(codecId)
         || CODEC_ID_DTS_LOSSLESS.equals(codecId)
+        || CODEC_ID_FLAC.equals(codecId)
         || CODEC_ID_SUBRIP.equals(codecId);
   }
 
@@ -1224,6 +1226,10 @@ public final class WebmExtractor implements Extractor {
         case CODEC_ID_DTS_LOSSLESS:
           mimeType = MimeTypes.AUDIO_DTS_HD;
           break;
+        case CODEC_ID_FLAC:
+          mimeType = MimeTypes.AUDIO_FLAC;
+          initializationData = Collections.singletonList(codecPrivate);
+          break;
         case CODEC_ID_SUBRIP:
           mimeType = MimeTypes.APPLICATION_SUBRIP;
           break;

library/src/main/java/com/google/android/exoplayer/util/MimeTypes.java

@@ -52,6 +52,7 @@ public final class MimeTypes {
   public static final String AUDIO_OPUS = BASE_TYPE_AUDIO + "/opus";
   public static final String AUDIO_AMR_NB = BASE_TYPE_AUDIO + "/3gpp";
   public static final String AUDIO_AMR_WB = BASE_TYPE_AUDIO + "/amr-wb";
+  public static final String AUDIO_FLAC = BASE_TYPE_AUDIO + "/x-flac";
 
   public static final String TEXT_VTT = BASE_TYPE_TEXT + "/vtt";