Remove buffered position edge case.

It's no longer safe to convert END_OF_SOURCE -> duration on
the main therad, since the Timeline from which the duration
is obtained is posted to the main thread, where-as the
buffered position is passed by updating a volatile. Hence
an update to the latter might become visible to the main
thread before the corresponding Timeline.

This change moves the conversion to the playback thread.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=130265893

library/src/main/java/com/google/android/exoplayer2/ExoPlayerImpl.java

@@ -141,7 +141,7 @@ import java.util.concurrent.CopyOnWriteArraySet;
 
   @Override
   public void seekTo(int periodIndex, long positionMs) {
-    boolean seekToDefaultPosition = positionMs == ExoPlayer.UNKNOWN_TIME;
+    boolean seekToDefaultPosition = positionMs == UNKNOWN_TIME;
     maskingPeriodIndex = periodIndex;
     maskingPositionMs = seekToDefaultPosition ? 0 : positionMs;
     pendingSeekAcks++;
@@ -155,7 +155,7 @@ import java.util.concurrent.CopyOnWriteArraySet;
 
   @Override
   public void seekToDefaultPosition(int periodIndex) {
-    seekTo(periodIndex, ExoPlayer.UNKNOWN_TIME);
+    seekTo(periodIndex, UNKNOWN_TIME);
   }
 
   @Override
@@ -212,7 +212,7 @@ import java.util.concurrent.CopyOnWriteArraySet;
   public long getBufferedPosition() {
     if (pendingSeekAcks == 0) {
       long bufferedPositionUs = playbackInfo.bufferedPositionUs;
-      return bufferedPositionUs == C.END_OF_SOURCE_US ? getDuration() : bufferedPositionUs / 1000;
+      return bufferedPositionUs == C.UNSET_TIME_US ? UNKNOWN_TIME : (bufferedPositionUs / 1000);
     } else {
       return maskingPositionMs;
     }
@@ -222,7 +222,7 @@ import java.util.concurrent.CopyOnWriteArraySet;
   public int getBufferedPercentage() {
     long bufferedPosition = getBufferedPosition();
     long duration = getDuration();
-    return bufferedPosition == ExoPlayer.UNKNOWN_TIME || duration == ExoPlayer.UNKNOWN_TIME ? 0
+    return bufferedPosition == UNKNOWN_TIME || duration == UNKNOWN_TIME ? 0
         : (int) (duration == 0 ? 100 : (bufferedPosition * 100) / duration);
   }
 

library/src/main/java/com/google/android/exoplayer2/ExoPlayerImplInternal.java

@@ -409,13 +409,10 @@ import java.io.IOException;
     elapsedRealtimeUs = SystemClock.elapsedRealtime() * 1000;
 
     // Update the buffered position.
-    long bufferedPositionUs;
-    if (enabledRenderers.length == 0) {
-      bufferedPositionUs = C.END_OF_SOURCE_US;
-    } else {
-      bufferedPositionUs = mediaPeriod.getBufferedPositionUs();
-    }
-    playbackInfo.bufferedPositionUs = bufferedPositionUs;
+    long bufferedPositionUs = enabledRenderers.length == 0 ? C.END_OF_SOURCE_US
+        : mediaPeriod.getBufferedPositionUs();
+    playbackInfo.bufferedPositionUs = bufferedPositionUs == C.END_OF_SOURCE_US
+        ? timeline.getPeriodDurationUs(playingPeriod.index) : bufferedPositionUs;
   }
 
   private void doSomeWork() throws ExoPlaybackException, IOException {