[HDA-Intel - HDA Intel PCH, playback] sound not working from browsers

[Jerry Quinn]

After upgrading to 16.04LTS, I no longer get sound from either chromium or firefox, tested on both youtube and facebook videos. Both "play" and "paplay" produce sound from the command line.

If I log in as a guest user, firefox can play audio - I didn't test chromium.

Something in the upgrade from 15.10 to 16.04 didn't agree with my existing settings.

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: alsa-base 1.0.25+dfsg-0ubuntu5
ProcVersionSignature: Ubuntu 4.4.0-22.40-generic 4.4.8
Uname: Linux 4.4.0-22-generic x86_64
ApportVersion: 2.20.1-0ubuntu2
Architecture: amd64
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC0: jlquinn 28492 F.... pulseaudio
 /dev/snd/controlC1: jlquinn 28492 F.... pulseaudio
CurrentDesktop: Unity
Date: Tue May 24 19:54:17 2016
InstallationDate: Installed on 2015-08-18 (280 days ago)
InstallationMedia: Ubuntu 15.04 "Vivid Vervet" - Release amd64 (20150422)
PackageArchitecture: all
SourcePackage: alsa-driver
Symptom: audio
Symptom_AudioUsers: pulse
Symptom_Card: Built-in Audio - HDA Intel PCH
Symptom_DevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC0: jlquinn 28492 F.... pulseaudio
                      lightdm 30783 F.... pulseaudio
 /dev/snd/controlC1: jlquinn 28492 F.... pulseaudio
                      lightdm 30783 F.... pulseaudio
Symptom_Jack: Speaker, Internal
Symptom_Type: Sound works for some users but not for others
Title: [HDA-Intel - HDA Intel PCH, playback] sound not working for all users
UpgradeStatus: Upgraded to xenial on 2016-04-28 (26 days ago)
dmi.bios.date: 03/12/2015
dmi.bios.vendor: LENOVO
dmi.bios.version: N14ET28W (1.06 )
dmi.board.asset.tag: Not Available
dmi.board.name: 20BS003BUS
dmi.board.vendor: LENOVO
dmi.board.version: SDK0E50510 WIN
dmi.chassis.asset.tag: No Asset Information
dmi.chassis.type: 10
dmi.chassis.vendor: LENOVO
dmi.chassis.version: None
dmi.modalias: dmi:bvnLENOVO:bvrN14ET28W(1.06):bd03/12/2015:svnLENOVO:pn20BS003BUS:pvrThinkPadX1Carbon3rd:rvnLENOVO:rn20BS003BUS:rvrSDK0E50510WIN:cvnLENOVO:ct10:cvrNone:
dmi.product.name: 20BS003BUS
dmi.product.version: ThinkPad X1 Carbon 3rd
dmi.sys.vendor: LENOVO