Many new phones move to navigation gestures from previous physical buttons. The idea is to maximize the screen space as much as possible and still be intuitive. Something cool you should know about, Chrome for iPhone and Android has a neat little trick that pairs quite nicely with these new gestures.
Instead of tapping the three-point menu button in any tab to bring up Chrome's options, press and swipe down if you're on Android, or press, pause, and swipe up if you're on the iPhone. From that point you can drag your finger over an item in the menu and then release to confirm your choice.
Usually you would press the menu, lift your finger, then tap the item in the list to confirm it. By using this quick gesture on Chrome, you get a faster and more seamless experience without having to lift a finger.