Where did the user agent field go in my Chrome DevTools?

There seems to be a lot of development happening on Device Mode. (E.g. if you try it out in Chrome Canary it looks very different.)

For now, you can customize the user agent like this:

1. Open the Console Drawer

2. Select "Network Conditions" in the dropdown in the console section.

3. Uncheck "Select Automatically", Select "custom user agent"

With Chrome Version 75.0.3770.100 (Windows) you can find it as below

1. Open Developer Tools and go to Network conditions setting

2. Open Network conditions. There you will find the User agent option set to Select automatically by default. Uncheck it to get a list of supported user agents.

You can also provide your custom user agent by selecting the Custom option from the list.