Update: As commenters have pointed out, the undo close tab option has been available before now - it's just the look that has changed. I've updated the screenshots to reflect this.
The beta edition of Chrome for Android is getting a small update before the changes go into the primary release. The biggest new addition in version 39.0.2171.37 is an "undo closed tab" option. When you swipe away a tab on the "all tabs" page, a contextual menu will appear at the bottom allowing you to instantly bring it back. This is standard behavior for desktop browsers - on Chrome for Windows, the Ctrl-Shift-T command does the same thing.
Chrome 38 on left, latest beta on the right
The fancy new Reader Mode (a feature that's been included in other mobile browsers for some time) is taking a back seat in this release. It's still there, but in order to see it in the latest Chrome 39 beta, you'll have to dive into the chrome://flags menu, enable the option, and restart the app.
The visuals for the Recent Tabs page have been altered slightly. The headers for connected devices with Chrome now appear in blue, making them easier to distinguish from the remote tabs themselves. A couple of fonts and icons have been switched as well, particularly for the hide/expand view for other devices.
39.0.2171.37 should be rolling out in the Play Store over the next few days. If you can't wait, we've included the APK download below.
The APK is signed by Google and upgrades your existing app. The cryptographic signature guarantees that the file is safe to install and was not tampered with in any way. Rather than wait for Google to push this download to your devices, which can take days, download and install it just like any other APK.
File name: com.chrome.beta-39.0.2171.37-2171037-minAPI14.apk
Version: 39.0.2171.37 (2171037) (Android 4.0+)