Revert of AudioPlayer: Update control panel with playback progress bar.

Revert of AudioPlayer: Update control panel with playback progress bar. (patchset #2 id:20001 of https://codereview.chromium.org/1403303011/ )

Reason for revert:
We decided to punt redesign of audio player to M49.

Original issue's description:
> AudioPlayer: Update control panel with playback progress bar.
>
> This CL includes:
> - Replace custom progress bar with paper-slider.
> - Pause track temporalily while dragging progress bar to be consistent with video player.
> - Adjust layout of control panel.
> - Show playing time as "{current} / {duration}".
>
> BUG=488229
> TEST=manually
>
> Committed: https://crrev.com/5c8f889bbbcc22b137b55e935e7d38f70c7e4ade
> Cr-Commit-Position: refs/heads/master@{#357064}

TBR=yawano@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=488229
Committed: https://crrev.com/5f691027fa2f7ea5f792308987a3ab166d58674c
Cr-Commit-Position: refs/heads/master@{#359286}

[fukino, 2015-11-12 08:33:01]

Created Revert of AudioPlayer: Update control panel with playback progress bar.

[commit-bot: I haz the power, 2015-11-12 08:33:14]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1442583002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1442583002/1

[commit-bot: I haz the power, 2015-11-12 08:34:21]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-11-12 20:06:02]

Patchset 1 (id:??) landed as
https://crrev.com/5f691027fa2f7ea5f792308987a3ab166d58674c
Cr-Commit-Position: refs/heads/master@{#359286}