Fix buffering state when selecting VTT track with no cues

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=137697023

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

@@ -95,7 +95,7 @@ import java.util.concurrent.atomic.AtomicInteger;
     this.extractorNeedsInit = extractorNeedsInit;
     this.shouldSpliceIn = shouldSpliceIn;
     // Note: this.dataSource and dataSource may be different.
-    adjustedEndTimeUs = startTimeUs;
+    adjustedEndTimeUs = endTimeUs;
     this.isEncrypted = this.dataSource instanceof Aes128DataSource;
     uid = UID_SOURCE.getAndIncrement();
   }