Background of this feature request in http://crosbug.com/p/55239

hychao@, I can certainly help this in chrome UI code. We need to loop in PM for this feature too. The following detail will need to be figured out:
1. We will need cras to assign a different node id and stable device id to line-out and headphone. Otherwise, these two device's state and settings can be mixed up.
2. What kind of priority the line-out should have, will be it the same as headphone?
3. We will need an icon from designer for line-out to display in the ash tray.

CRAS side change at: https://chromium-review.googlesource.com/#/c/363663/5
audio/audio_device change at: https://codereview.chromium.org/2222903002/

with above two CLs, Chrome UI can get the line-out node type reported by CRAS.
I think line-out node should have the same priority and default volume as 'headphone' node. We will let partner configure separate volume curve for line-out audio device.

kuscher@, I have LGTMed hychao's cl for the adding the line-out output device type. Once it lands, I can finish the UI code to expose the device in UI. We will need to add a new icon this the line-out speaker. Can you find someone to help us?

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/4a8395b5715c5dc4d0e84353e814f5a08cd29742

commit 4a8395b5715c5dc4d0e84353e814f5a08cd29742
Author: hychao <hychao@chromium.org>
Date: Tue Aug 16 03:30:12 2016

audio_device: Add lineout node type

BUG=633467
R=jennyz@chromium.org

Review-Url: https://codereview.chromium.org/2222903002
Cr-Commit-Position: refs/heads/master@{#412158}

[modify] https://crrev.com/4a8395b5715c5dc4d0e84353e814f5a08cd29742/chromeos/audio/audio_device.cc
[modify] https://crrev.com/4a8395b5715c5dc4d0e84353e814f5a08cd29742/chromeos/audio/audio_device.h

We have device supporting line-out using M54 as FSI.

kuscher@, can you fine someone to make a new icon for the line-out device?

54 has already branched.  I'm not convinced that showing the "correct" icon when a line out device is connected justifies a merge.  By the time we get an icon created and agree on it, it would likely be a fairly late merge.

If someone feels strongly we can discuss, but I'm punting this to 55.

We have device with lineout support in M56. Can we target this feature at M56?

56 is already in feature freeze and it looks like we don't have assets for this yet.

@sgabriel could you share a line out icon? Some examples here: https://en.wikipedia.org/wiki/Line_level#Line_out

We already have a line-out icon that are used in the sub-panel. I attached they assets. Would that work?

Deleted: output.zip 1.5 KB

output.zip 1.5 KB Download

Given we're so close to m-56 stable, any further changes here should almost certainly not be targeted at m-56. Punting to m-58. tbuckley@, please re-triage if you disagree.

jennyz@ friendly ping - just curious about the status of this issue.