If you wish to use the Chrome web browser on a Mac with a proxy different from the system settings in Chrome, one such reason might be using Burp Suite whilst also using your browser normally, then this is a possible configuration.
Download Chrome Canary, which defaults to its own profile, and mount the disk image then command:
open -a /Volumes/Google\ Chrome\ Canary/Google\ Chrome\ Canary.app/Contents/MacOS/Google\ Chrome\ Canary --args --proxy-server=127.0.0.1:8080
Will enable the browser to talk to a proxy on 127.0.0.1:8080 for HTTP and HTTPS without affecting the system proxies.
This allows testing apps with a very modern Chrome instance with no messing about local proxy settings, and running two versions of Chrome side by side easily.
The HTTP/HTTPS means it isn’t suitable for websocket based applications.
If using Burp Suite you will still need to import the CA certificate into Key Chain access and Trust it.
Note if you don’t install Chrome Canary the pop-up to install it doesn’t steal focus, so may end up immediately beneath the Terminal in which you ran the “open” command.