@tdanderson, can you help triage?

We're planning a milestone or two of code health and PE fixes related to the shelf and system menu, so adding Proj-MaterialDesign-CrOS so this is tracked as a candidate.

 Issue 687350  has been merged into this issue.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/b698a2cc70ef266c593b7515881c0dbf60106a17

commit b698a2cc70ef266c593b7515881c0dbf60106a17
Author: mohsen <mohsen@chromium.org>
Date: Tue Mar 28 01:09:24 2017

Remove TrayAudioDelegate

TrayAudioDelegate was needed when Ash was supported on Windows.
Currently, the only implementation is Chrome OS implementation which can
now be inlined wherever the delegate was used.

BUG= 664642 
TEST=none

Review-Url: https://codereview.chromium.org/2778503002
Cr-Commit-Position: refs/heads/master@{#459963}

[modify] https://crrev.com/b698a2cc70ef266c593b7515881c0dbf60106a17/ash/BUILD.gn
[modify] https://crrev.com/b698a2cc70ef266c593b7515881c0dbf60106a17/ash/common/system/chromeos/audio/tray_audio.cc
[modify] https://crrev.com/b698a2cc70ef266c593b7515881c0dbf60106a17/ash/common/system/chromeos/audio/tray_audio.h
[delete] https://crrev.com/7a72d526a580b3727a91ed5e21a5d4af9fc548b6/ash/common/system/chromeos/audio/tray_audio_delegate.h
[delete] https://crrev.com/7a72d526a580b3727a91ed5e21a5d4af9fc548b6/ash/common/system/chromeos/audio/tray_audio_delegate_chromeos.cc
[delete] https://crrev.com/7a72d526a580b3727a91ed5e21a5d4af9fc548b6/ash/common/system/chromeos/audio/tray_audio_delegate_chromeos.h
[modify] https://crrev.com/b698a2cc70ef266c593b7515881c0dbf60106a17/ash/common/system/chromeos/audio/volume_view.cc
[modify] https://crrev.com/b698a2cc70ef266c593b7515881c0dbf60106a17/ash/common/system/chromeos/audio/volume_view.h