Google started offering Chrome Custom Tabs in v45 as a way to open links, and some app developers have started taking advantage of the faster rendering and Chrome data integration. Now, Google appears to be taking matters into its own hands to make links load faster when you use Chrome Dev. Some users are seeing Chrome Custom Tabs loading for all apps when Chrome Dev is set as the default.

With Chrome Dev, links from other apps will now open in a Custom Tab, which loads much faster than the full browser. Custom Tabs also support form completion, shared logins, and more. You can still use the toolbar button in these Custom Tabs to pop over to the full Chrome Dev. Some apps like Chromer have popped up to do essentially the same thing that Chrome Dev is now doing. If this is going to become a feature of Chrome stable, it would appear Chromer's reason for existing has gone away.

I should stress this is not happening for everyone, and we don't know for sure what's causing it. There may be some flag in the app or a sever-side switch that's causing it. A few people on the team are seeing this feature, though. You might as well grab the latest version of Chrome Dev from APK Mirror to see if that enables the feature for you.