function exitVRSuccess () {
          self.removeState('vr-mode');
          // Lock to landscape orientation on mobile.
          if (self.isMobile && screen.orientation && screen.orientation.unlock) {
            screen.orientation.unlock();
          }
          // Exiting VR in embedded mode, no longer need fullscreen styles.
          if (self.hasAttribute('embedded')) { self.removeFullScreenStyles(); }
          self.resize();
          if (self.isIOS) { utils.forceCanvasResizeSafariMobile(this.canvas); }
          self.emit('exit-vr', {target: self});
        }
Call `exitPresent` if WebVR or WebVR polyfill.
Handle events, states, fullscreen styles.

@param {bool} fromExternal - Whether exiting VR due to an external event (e.g.,
  Oculus Browser GearVR back button).
@returns {Promise}