
Also prevents that we try to restore audio mode when it has not been changed. TBR=glaznev BUG=NONE TEST=AppRTCDemo and verify that volume control switches from "Ringtone to Phone" mode when call starts and switches back to Ringtone mode when call ends. Review URL: https://webrtc-codereview.appspot.com/46879004 Cr-Commit-Position: refs/heads/master@{#8975}