Improve track index adjustment logic by adding index comparison

[jaeho-lee104]

If the conditions are not suitable, it will use the value of the previousSelectedIndex.
so if the previousSelectedIndex and newSelectedIndex are the same, there is no need to perform that logic.

current implementation

if (!isTrackExcluded(previousSelectedIndex, nowMs)) {
  // Revert back to the previous selection if conditions are not suitable for switching.
  Format currentFormat = getFormat(previousSelectedIndex);
  Format selectedFormat = getFormat(newSelectedIndex);
  long minDurationForQualityIncreaseUs =
      minDurationForQualityIncreaseUs(availableDurationUs, chunkDurationUs);
  if (selectedFormat.bitrate > currentFormat.bitrate
      && bufferedDurationUs < minDurationForQualityIncreaseUs) {
    // The selected track is a higher quality, but we have insufficient buffer to safely switch
    // up. Defer switching up for now.
    newSelectedIndex = previousSelectedIndex;
  } else if (selectedFormat.bitrate < currentFormat.bitrate
      && bufferedDurationUs >= maxDurationForQualityDecreaseUs) {
    // The selected track is a lower quality, but we have sufficient buffer to defer switching
    // down for now.
    newSelectedIndex = previousSelectedIndex;
  }
}

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[jaeho-lee104]

@oceanjules @tianyif Hi, thanks for reviewing this pull request.
Have been waiting on a response for some time now.
Please let me know if there is anything I need to do. Thanks.

[tianyif]

I'm going to send this for internal review now. You may see some more commits being added as I make changes in response to review feedback. Please refrain from pushing any more substantive changes as it will complicate the internal review - thanks!

[tianyif]

This change has been submitted to the internal repo, you will see it appear in the dev branch next week. No action required at this point. Thanks for the contribution!

[jaeho-lee104]

Thanks for the comment.
Thanks!