Fix 2 CEA decoder bugs

1- Avoid dropped buffers by using a PriorityQueue instead of a set.
2- Process the end of stream after non-EOS buffers.

Issue:#3250

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=169077365

library/core/src/main/java/com/google/android/exoplayer2/text/SubtitleInputBuffer.java

@@ -37,6 +37,9 @@ public final class SubtitleInputBuffer extends DecoderInputBuffer
 
   @Override
   public int compareTo(@NonNull SubtitleInputBuffer other) {
+    if (isEndOfStream() != other.isEndOfStream()) {
+      return isEndOfStream() ? 1 : -1;
+    }
     long delta = timeUs - other.timeUs;
     if (delta == 0) {
       return 0;

library/core/src/main/java/com/google/android/exoplayer2/text/TextRenderer.java

@@ -37,7 +37,7 @@ import java.util.List;
  * <p>
  * {@link Subtitle}s are decoded from sample data using {@link SubtitleDecoder} instances obtained
  * from a {@link SubtitleDecoderFactory}. The actual rendering of the subtitle {@link Cue}s is
- * delegated to an {@link TextOutput}.
+ * delegated to a {@link TextOutput}.
  */
 public final class TextRenderer extends BaseRenderer implements Callback {
 
@@ -291,9 +291,9 @@ public final class TextRenderer extends BaseRenderer implements Callback {
   }
 
   private long getNextEventTime() {
-    return ((nextSubtitleEventIndex == C.INDEX_UNSET)
-        || (nextSubtitleEventIndex >= subtitle.getEventTimeCount())) ? Long.MAX_VALUE
-        : (subtitle.getEventTime(nextSubtitleEventIndex));
+    return nextSubtitleEventIndex == C.INDEX_UNSET
+        || nextSubtitleEventIndex >= subtitle.getEventTimeCount()
+        ? Long.MAX_VALUE : subtitle.getEventTime(nextSubtitleEventIndex);
   }
 
   private void updateOutput(List<Cue> cues) {

library/core/src/main/java/com/google/android/exoplayer2/text/cea/CeaDecoder.java

@@ -24,7 +24,7 @@ import com.google.android.exoplayer2.text.SubtitleInputBuffer;
 import com.google.android.exoplayer2.text.SubtitleOutputBuffer;
 import com.google.android.exoplayer2.util.Assertions;
 import java.util.LinkedList;
-import java.util.TreeSet;
+import java.util.PriorityQueue;
 
 /**
  * Base class for subtitle parsers for CEA captions.
@@ -36,7 +36,7 @@ import java.util.TreeSet;
 
   private final LinkedList<SubtitleInputBuffer> availableInputBuffers;
   private final LinkedList<SubtitleOutputBuffer> availableOutputBuffers;
-  private final TreeSet<SubtitleInputBuffer> queuedInputBuffers;
+  private final PriorityQueue<SubtitleInputBuffer> queuedInputBuffers;
 
   private SubtitleInputBuffer dequeuedInputBuffer;
   private long playbackPositionUs;
@@ -50,7 +50,7 @@ import java.util.TreeSet;
     for (int i = 0; i < NUM_OUTPUT_BUFFERS; i++) {
       availableOutputBuffers.add(new CeaOutputBuffer(this));
     }
-    queuedInputBuffers = new TreeSet<>();
+    queuedInputBuffers = new PriorityQueue<>();
   }
 
   @Override
@@ -73,7 +73,6 @@ import java.util.TreeSet;
 
   @Override
   public void queueInputBuffer(SubtitleInputBuffer inputBuffer) throws SubtitleDecoderException {
-    Assertions.checkArgument(inputBuffer != null);
     Assertions.checkArgument(inputBuffer == dequeuedInputBuffer);
     if (inputBuffer.isDecodeOnly()) {
       // We can drop this buffer early (i.e. before it would be decoded) as the CEA formats allow
@@ -90,13 +89,12 @@ import java.util.TreeSet;
     if (availableOutputBuffers.isEmpty()) {
       return null;
     }
-
     // iterate through all available input buffers whose timestamps are less than or equal
     // to the current playback position; processing input buffers for future content should
     // be deferred until they would be applicable
     while (!queuedInputBuffers.isEmpty()
-        && queuedInputBuffers.first().timeUs <= playbackPositionUs) {
-      SubtitleInputBuffer inputBuffer = queuedInputBuffers.pollFirst();
+        && queuedInputBuffers.peek().timeUs <= playbackPositionUs) {
+      SubtitleInputBuffer inputBuffer = queuedInputBuffers.poll();
 
       // If the input buffer indicates we've reached the end of the stream, we can
       // return immediately with an output buffer propagating that
@@ -142,7 +140,7 @@ import java.util.TreeSet;
   public void flush() {
     playbackPositionUs = 0;
     while (!queuedInputBuffers.isEmpty()) {
-      releaseInputBuffer(queuedInputBuffers.pollFirst());
+      releaseInputBuffer(queuedInputBuffers.poll());
     }
     if (dequeuedInputBuffer != null) {
       releaseInputBuffer(dequeuedInputBuffer);