Add ondevicechange event support to demo

[markafoltz]

Demo does not use devicechange event to keep device selectors in sync with hotplug. This fixes the demo to do that.

It also fixes some other issues:

• The demo now works if only a camera or mic is available (but not both)
• The demo waits for enumeration to complete before calling gUM. Previously, this would result in a failed request.

console.log will be removed before merging.

[markafoltz]

This should be ready for review. Who can take a look? @handellm @henbos @fippo

[fippo]

Nice! eslint --fix should be able to deal with the lint failures

[fippo]

(maybe reduce the console.log amount but... I like console.log)

[handellm]

I tried the patched demo, with repository checked out and python3 -m http.server serving the files and navigating to localhost. Things started out not working, probably there was something strange about permissions. After accepting cam & mike permissions things jumped to life and worked well.

+1 on fixing lint failures otherwise lgtm.

[guidou]

lgtm % the automated comments (var -> let/const and spaces)

[markafoltz]

eslint --fix should be able to deal with the lint failures

This seems broken for me:

$ eslint --fix main.js

Oops! Something went wrong! :(

ESLint: 6.4.0.

ESLint couldn't find the config "google" to extend from. Please check that the name of the config is correct.

The config "google" was referenced from the config file in "/home/mfoltz/github/markafoltz/webrtc-samples/.eslintrc.js".

I will fix manually instead.

[markafoltz]

Things started out not working, probably there was something strange about permissions.

Yeah. If you call enumerateDevices() without permissions it returns dummy values with empty deviceIds, but the demo would populate the dropdowns anyway.

I updated it to avoid populating the dropdowns with dummy values, so permission is requested right away and then the dropdowns can get the true values.

[markafoltz]

Okay, this should be ready for another look and a merge if there are no more comments.

[fippo]

(something weird with webdriver these days, needs investigation)