HLS: Instantiate an AC3 extractor for .ec3 files

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=132417755

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

@@ -99,6 +99,7 @@ import java.util.Locale;
   private static final String TAG = "HlsChunkSource";
   private static final String AAC_FILE_EXTENSION = ".aac";
   private static final String AC3_FILE_EXTENSION = ".ac3";
+  private static final String EC3_FILE_EXTENSION = ".ec3";
   private static final String MP3_FILE_EXTENSION = ".mp3";
   private static final String VTT_FILE_EXTENSION = ".vtt";
   private static final String WEBVTT_FILE_EXTENSION = ".webvtt";
@@ -335,7 +336,8 @@ import java.util.Locale;
       // identifier com.apple.streaming.transportStreamTimestamp. This may also apply to the MP3
       // case below.
       extractor = new AdtsExtractor(startTimeUs);
-    } else if (lastPathSegment.endsWith(AC3_FILE_EXTENSION)) {
+    } else if (lastPathSegment.endsWith(AC3_FILE_EXTENSION)
+        || lastPathSegment.endsWith(EC3_FILE_EXTENSION)) {
       extractor = new Ac3Extractor(startTimeUs);
     } else if (lastPathSegment.endsWith(MP3_FILE_EXTENSION)) {
       extractor = new Mp3Extractor(startTimeUs);