Reddirt that isn't a result of the new file.
I might be wrong, but you may need to play around with "Use Custom Audio Device" settings in the Chrome Addon.
First find the correct Audio device by connecting to SSH of your libreelec device, when connected run: aplay -l
Then define that in the plugin.
I'll use my situation as an example:
aplay -l
**** List of PLAYBACK Hardware Devices ****
card 0: PCH [HDA Intel PCH], device 0: ALC233 Analog [ALC233 Analog]
Subdevices: 1/1
Subdevice #0: subdevice #0
card 0: PCH [HDA Intel PCH], device 3: HDMI 0 [HDMI 0]
Subdevices: 0/1
Subdevice #0: subdevice #0
card 0: PCH [HDA Intel PCH], device 7: HDMI 1 [HDMI 1]
Subdevices: 1/1
Subdevice #0: subdevice #0
card 0: PCH [HDA Intel PCH], device 8: HDMI 2 [HDMI 2]
Subdevices: 1/1
Subdevice #0: subdevice #0
card 0: PCH [HDA Intel PCH], device 9: HDMI 3 [HDMI 3]
Subdevices: 1/1
Subdevice #0: subdevice #0
card 0: PCH [HDA Intel PCH], device 10: HDMI 4 [HDMI 4]
Subdevices: 1/1
Subdevice #0: subdevice #0
Display More
I then looked at the Audio settings in Kodi and saw that I'm using: ALSA: HDA Intel PCH, DON DENON-AVRHD on DisplayPort #0
Seeing there was no DisplayPort 0 returned in the aplay I figured that's just HDMI 0 (same same, but different).
So that meant, Card 0, Device 3
I then went to the Chrome addon, enabled "Use Custom Audio Device" and entered: plughw:0,3
Gave the system a reboot just to be sure and now I had audio from Chrome whatever I did.
Sound problem in Chrome for more info and links to other topics.
Please note: Just entering plughw:0,7 in your case, based of my results will probably not help you, it's really needed that you'll run your own aplay -l on the Libreelec box, interpret your own results and define the plughw: based on your situation.
Hope it helps!