Fix buffered position when loading has not completed

If there is data after the last samples in the container, we may request
continue loading after the last samples have been read but before the load has
completed. In this situation the buffered position is returned as
Long.MAX_VALUE, which prevents continuing loading, yet the media period is not
treated as fully buffered because its buffered position is not
C.TIME_END_OF_SOURCE.

PiperOrigin-RevId: 231406964

library/core/src/main/java/com/google/android/exoplayer2/source/ExtractorMediaPeriod.java

@@ -346,10 +346,9 @@ public long getBufferedPositionUs() {
     } else if (isPendingReset()) {
       return pendingResetPositionUs;
     }
-    long largestQueuedTimestampUs = C.TIME_UNSET;
+    long largestQueuedTimestampUs = Long.MAX_VALUE;
     if (haveAudioVideoTracks) {
       // Ignore non-AV tracks, which may be sparse or poorly interleaved.
-      largestQueuedTimestampUs = Long.MAX_VALUE;
       int trackCount = sampleQueues.length;
       for (int i = 0; i < trackCount; i++) {
         if (trackIsAudioVideoFlags[i] && !sampleQueues[i].isLastSampleQueued()) {
@@ -358,7 +357,7 @@ public long getBufferedPositionUs() {
         }
       }
     }
-    if (largestQueuedTimestampUs == C.TIME_UNSET) {
+    if (largestQueuedTimestampUs == Long.MAX_VALUE) {
       largestQueuedTimestampUs = getLargestQueuedTimestampUs();
     }
     return largestQueuedTimestampUs == Long.MIN_VALUE ? lastSeekPositionUs