Audio Player: Don't update the track list when the list is not changed
Previously, when user clicked the audio file on Files.app, the track list was updated unexpectedly and the current track index was set to the default (the first file) for a very short time just before the index was updated to the selected file. This unexpected change in short period made the playback time reset and caused the issue (crbug.com/395868). This patch fixes this issue.
BUG=395868
TEST=none
Review URL: https://codereview.chromium.org/
515443002
Cr-Commit-Position: refs/heads/master@{#292565}