Fix subtitles.

library/src/main/java/com/google/android/exoplayer/chunk/SingleSampleMediaChunk.java

@@ -118,7 +118,7 @@ public final class SingleSampleMediaChunk extends BaseMediaChunk {
       if (headerData != null) {
         sampleSize += headerData.length;
       }
-      getOutput().sampleMetadata(startTimeUs, 0, sampleSize, 0, null);
+      getOutput().sampleMetadata(startTimeUs, C.SAMPLE_FLAG_SYNC, sampleSize, 0, null);
     } finally {
       dataSource.close();
     }

library/src/main/java/com/google/android/exoplayer/text/TextTrackRenderer.java

@@ -179,7 +179,7 @@ public class TextTrackRenderer extends TrackRenderer implements Callback {
         SampleHolder sampleHolder = parserHelper.getSampleHolder();
         sampleHolder.clearData();
         int result = source.readData(trackIndex, positionUs, formatHolder, sampleHolder, false);
-        if (result == SampleSource.SAMPLE_READ && !sampleHolder.isDecodeOnly()) {
+        if (result == SampleSource.SAMPLE_READ) {
           parserHelper.startParseOperation();
           textRendererNeedsUpdate = false;
         } else if (result == SampleSource.END_OF_STREAM) {