Answer by Christopher for How to get Google Apps Launcher, Google Now, and Notifications

To get the Google App Launcher on your Ubuntu Unity task bar:

1. Install the Google Chrome browser
2. Launch Google Chrome and enter the address chrome://flags/#enable-app-list
3. Click enable for the setting named Enable the App Launcher. Linux
4. Open the Unity Launcher and type Chrome App to find the Chrome App Launcher in your Applications list
5. Launch the Chrome App Launcher and you should see the icon appear in the Unity Launcher sidebar
6. Right-click on the Chrome App Launcher in the Unity Launcher sidebar and select Lock to Launcher
7. Now hold a left-click and then drag the Chrome App Launcher icon up to the top of the Unity Launcher sidebar so it is just below the Unity Launcher icon at top-right

You should now have a Google App Launcher in your Unity Launcher sidebar that provides a handy shortcut to your most used Google applications. You should also ensure that the Google Chrome browser is set to run in the background so that you continue to get notifications from Hangouts and other applications. To do that, just

1. launch the Google Chrome browser,
2. Find the icon in the notifications area (top-right of the desktop)
3. Left-click on the icon and check the option to Let Google Chrome run in the background

Google Chrome notifications settings can be controlled from the Google Chrome browser settings. Instructions for these are outlined on this Advanced Chrome Help topic titled Turn notifications on or off