You can get the three-button navigation bar back on Android by opening Settings and selecting 3-button Navigation under ...

How to set up an Action Button on Android with a mapping app Most features with customizable buttons on Android phones are part of the touchscreen. That's nice, but not exactly an Action Button.

A new Google app beta tries removing the prominent Search button from the screen-bottom nav bar. Google appears to be experimenting with several alternate layouts for the navigation interface.