Another repro steps:
1. Plug in a USB headset and 3.5mm headset
2. Select the 3.5mm headset for audio out
3. Unplug usb headset
4. Unplug 35mm headphone.
5. Plug in usb headset.

Expected:
Audio should come from USB Headset
Actual:
Audio still comes out of the speakers. This needs to be fixed.

The key lies in usb was unplugged when it is not active.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/7e77e3684bd82c839a97544ea1aab897c1cfc74e

commit 7e77e3684bd82c839a97544ea1aab897c1cfc74e
Author: Jenny Zhang <jennyz@chromium.org>
Date: Tue Sep 26 18:26:57 2017

Fix the issue of usb headphone is not active when plugged in after rebooting.

Bug:  767245 
Change-Id: I059d4e783510b9dd3b5db5e8cfd7312e9cd43146
Reviewed-on: https://chromium-review.googlesource.com/679934
Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Reviewed-by: Jenny Zhang <jennyz@chromium.org>
Commit-Queue: Jenny Zhang <jennyz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#504429}
[modify] https://crrev.com/7e77e3684bd82c839a97544ea1aab897c1cfc74e/chromeos/audio/cras_audio_handler.cc
[modify] https://crrev.com/7e77e3684bd82c839a97544ea1aab897c1cfc74e/chromeos/audio/cras_audio_handler_unittest.cc