Force single audio and video sample queues

This solves the problem of having dense tracks' ids change.
For example, if the available variants offer both HEVC and AVC video
tracks, all video samples will map to the same sample queue even if
IDs don't match.

Issue:#3653

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=182070486

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

@@ -156,7 +156,7 @@ import java.util.concurrent.atomic.AtomicInteger;
    */
   public void init(HlsSampleStreamWrapper output) {
     this.output = output;
-    output.init(uid, shouldSpliceIn);
+    output.init(uid, shouldSpliceIn, reusingExtractor);
     if (!reusingExtractor) {
       extractor.init(output);
     }

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

@@ -93,6 +93,10 @@ import java.util.Arrays;
 
   private SampleQueue[] sampleQueues;
   private int[] sampleQueueTrackIds;
+  private boolean audioSampleQueueMappingDone;
+  private int audioSampleQueueIndex;
+  private boolean videoSampleQueueMappingDone;
+  private int videoSampleQueueIndex;
   private boolean sampleQueuesBuilt;
   private boolean prepared;
   private int enabledTrackGroupCount;
@@ -143,6 +147,8 @@ import java.util.Arrays;
     loader = new Loader("Loader:HlsSampleStreamWrapper");
     nextChunkHolder = new HlsChunkSource.HlsChunkHolder();
     sampleQueueTrackIds = new int[0];
+    audioSampleQueueIndex = C.INDEX_UNSET;
+    videoSampleQueueIndex = C.INDEX_UNSET;
     sampleQueues = new SampleQueue[0];
     sampleQueueIsAudioVideoFlags = new boolean[0];
     sampleQueuesEnabledStates = new boolean[0];
@@ -616,8 +622,14 @@ import java.util.Arrays;
    * @param chunkUid The chunk's uid.
    * @param shouldSpliceIn Whether the samples parsed from the chunk should be spliced into any
    *     samples already queued to the wrapper.
+   * @param reusingExtractor Whether the extractor for the chunk has already been used for preceding
+   *     chunks.
    */
-  public void init(int chunkUid, boolean shouldSpliceIn) {
+  public void init(int chunkUid, boolean shouldSpliceIn, boolean reusingExtractor) {
+    if (!reusingExtractor) {
+      audioSampleQueueMappingDone = false;
+      videoSampleQueueMappingDone = false;
+    }
     for (SampleQueue sampleQueue : sampleQueues) {
       sampleQueue.sourceId(chunkUid);
     }
@@ -633,14 +645,43 @@ import java.util.Arrays;
   @Override
   public TrackOutput track(int id, int type) {
     int trackCount = sampleQueues.length;
-    for (int i = 0; i < trackCount; i++) {
-      if (sampleQueueTrackIds[i] == id) {
-        return sampleQueues[i];
+
+    // Audio and video tracks are handled manually to ignore ids.
+    if (type == C.TRACK_TYPE_AUDIO) {
+      if (audioSampleQueueIndex != C.INDEX_UNSET) {
+        if (audioSampleQueueMappingDone) {
+          return sampleQueueTrackIds[audioSampleQueueIndex] == id
+              ? sampleQueues[audioSampleQueueIndex]
+              : createDummyTrackOutput(id, type);
+        }
+        audioSampleQueueMappingDone = true;
+        sampleQueueTrackIds[audioSampleQueueIndex] = id;
+        return sampleQueues[audioSampleQueueIndex];
+      } else if (tracksEnded) {
+        return createDummyTrackOutput(id, type);
+      }
+    } else if (type == C.TRACK_TYPE_VIDEO) {
+      if (videoSampleQueueIndex != C.INDEX_UNSET) {
+        if (videoSampleQueueMappingDone) {
+          return sampleQueueTrackIds[videoSampleQueueIndex] == id
+              ? sampleQueues[videoSampleQueueIndex]
+              : createDummyTrackOutput(id, type);
+        }
+        videoSampleQueueMappingDone = true;
+        sampleQueueTrackIds[videoSampleQueueIndex] = id;
+        return sampleQueues[videoSampleQueueIndex];
+      } else if (tracksEnded) {
+        return createDummyTrackOutput(id, type);
+      }
+    } else /* sparse track */ {
+      for (int i = 0; i < trackCount; i++) {
+        if (sampleQueueTrackIds[i] == id) {
+          return sampleQueues[i];
+        }
+      }
+      if (tracksEnded) {
+        return createDummyTrackOutput(id, type);
       }
-    }
-    if (tracksEnded) {
-      Log.w(TAG, "Unmapped track with id " + id + " of type " + type);
-      return new DummyTrackOutput();
     }
     SampleQueue trackOutput = new SampleQueue(allocator);
     trackOutput.setSampleOffsetUs(sampleOffsetUs);
@@ -653,6 +694,13 @@ import java.util.Arrays;
     sampleQueueIsAudioVideoFlags[trackCount] = type == C.TRACK_TYPE_AUDIO
         || type == C.TRACK_TYPE_VIDEO;
     haveAudioVideoSampleQueues |= sampleQueueIsAudioVideoFlags[trackCount];
+    if (type == C.TRACK_TYPE_AUDIO) {
+      audioSampleQueueMappingDone = true;
+      audioSampleQueueIndex = trackCount;
+    } else if (type == C.TRACK_TYPE_VIDEO) {
+      videoSampleQueueMappingDone = true;
+      videoSampleQueueIndex = trackCount;
+    }
     sampleQueuesEnabledStates = Arrays.copyOf(sampleQueuesEnabledStates, trackCount + 1);
     return trackOutput;
   }
@@ -913,4 +961,9 @@ import java.util.Arrays;
     }
     return true;
   }
+
+  private static DummyTrackOutput createDummyTrackOutput(int id, int type) {
+    Log.w(TAG, "Unmapped track with id " + id + " of type " + type);
+    return new DummyTrackOutput();
+  }
 }