Fix NPE when trying to play H265 in Ts files

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=136607848

library/src/main/java/com/google/android/exoplayer2/extractor/ts/H265Reader.java

@@ -44,6 +44,7 @@ import java.util.Collections;
   private static final int SUFFIX_SEI_NUT = 40;
 
   private TrackOutput output;
+  private SampleReader sampleReader;
   private SeiReader seiReader;
 
   // State that should not be reset on seek.
@@ -56,7 +57,6 @@ import java.util.Collections;
   private final NalUnitTargetBuffer pps;
   private final NalUnitTargetBuffer prefixSei;
   private final NalUnitTargetBuffer suffixSei; // TODO: Are both needed?
-  private final SampleReader sampleReader;
   private long totalBytesWritten;
 
   // Per packet state that gets reset at the start of each packet.
@@ -72,7 +72,6 @@ import java.util.Collections;
     pps = new NalUnitTargetBuffer(PPS_NUT, 128);
     prefixSei = new NalUnitTargetBuffer(PREFIX_SEI_NUT, 128);
     suffixSei = new NalUnitTargetBuffer(SUFFIX_SEI_NUT, 128);
-    sampleReader = new SampleReader(output);
     seiWrapper = new ParsableByteArray();
   }
 
@@ -91,6 +90,7 @@ import java.util.Collections;
   @Override
   public void init(ExtractorOutput extractorOutput, TrackIdGenerator idGenerator) {
     output = extractorOutput.track(idGenerator.getNextId());
+    sampleReader = new SampleReader(output);
     seiReader = new SeiReader(extractorOutput.track(idGenerator.getNextId()));
   }