Chrome Version: 61.0.3142.0
OS: 9693.0.0 dev-channel Cyan

What steps will reproduce the problem?
(1) Sign in to device
(2) Play some audio on youtube
(3) Now connect the external monitor using HDMI cable to the device
(4) Press ctrl + f4 to put the device in mirror mode (Mirror image shows on the external monitor and audio is heard from the external monitor)
(5) Unplug the external monitor while in mirror mode and audio playing

What is the expected result?
HDMI output should not be shown as active in the uber tray and audio should be heard from the internal speakers

What happens instead?
1) HDMI output is still shown and as active in uber tray
2) Audio is not heard from internal speakers
3) cras_test_client --dump_server_info shows as HDMI as active Output nodes 
4) Able to get screenshots for both internal display and external monitor

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Logs and screenshots attached.

For graphics-related bugs, please copy/paste the contents of the about:gpu
page at the end of this report.