Google has nearly completed the process of removing the merged apps/tabs option from Chrome after the option was pulled from the recent beta build. But what comes next? The Chromium bug tracker hinted at a new feature called Herb in Chrome v52, and indeed, there are several flavors of Herb in the new dev update.
The flavors of Herb are actually named after herbs, because that's how Google is. You'll have to grab the app from APK Mirror and access the flag to play around with Herb. You'll find it here chrome://flags/#tab-management-experiment-type .
Before we get to Herb, one other small note. There's a flag to change the look of the Chrome media notifications so they match Android's darker media UI. See below.
Keep in mind, this is an experiment in a dev browser. Some things just don't work, especially on tablets. Right now there are five flavors of Herb that determine how links are handled in the browser and app switcher (CCT means Chrome Custom Tab, and CTA is CustomTabActivity). The flavors mix and match a few features that make subtle changes to how links are opened.
So, let's say you choose Anise. View intents will open in a standard custom tab and the browser will use regular CTA (just a browser tab in this context, as far as I can tell). This all shows up under the Chrome Dev process in recents. Look at Basil, though. That will open view intents in a custom tab and other links in a "CTA with X." That means those tabs will have an "X" in place of the browser home button—it's a return trigger that immediately sends you back to the "calling app" you were just in.
Left: Herb flavors, Middle: Basil with the return button, Right: Elderberry with the new custom tab
Where things get interesting is with the Chrome Custom Tab v2 setting in Elderberry. This one opens all view intents in the new v2 custom tabs. These show up in the recent apps list as separate entries (see above), but regular Chrome tabs you might have open are still all contained within Chrome. We'll probably see this feature evolve over time before any of the flavors become a default setting.