The navigation controller is used to display the title of the app and to feature the settings button. This work is foundation for adding settings screen to the app (see webrtc:6473 for more info) BUG=webrtc:6618, webrtc:6473 Review-Url: https://codereview.webrtc.org/2455363002 Cr-Commit-Position: refs/heads/master@{#14816}