Add video codec setting to AppRTCMobile on iOS.

webrtc/examples/objc/AppRTCMobile/ios/ARDVideoCallViewController.m

Index: webrtc/examples/objc/AppRTCMobile/ios/ARDVideoCallViewController.m
diff --git a/webrtc/examples/objc/AppRTCMobile/ios/ARDVideoCallViewController.m b/webrtc/examples/objc/AppRTCMobile/ios/ARDVideoCallViewController.m
index 9e17951f07f587d71d43372e8dd2a730c93e6155..22fd2dc2728bf96791ff0c7193b26f0dbffbd93b 100644
--- a/webrtc/examples/objc/AppRTCMobile/ios/ARDVideoCallViewController.m
+++ b/webrtc/examples/objc/AppRTCMobile/ios/ARDVideoCallViewController.m
@@ -51,6 +51,7 @@
         initWithMandatoryConstraints:nil
                  optionalConstraints:[settingsModel
                                          currentMediaConstraintFromStoreAsRTCDictionary]];
+    [_client setVideoCodec:[settingsModel currentVideoCodecSettingFromStore]];

[kthelgason, 2017/03/10 10:41:44]

I realize that this is just copying the style below but it should rather be
`client.videoCodec =` for properties.

Also, consider making the property read-only and passing it in the initializer.
Seems safer to me since we make the assumption in ARDAppClient that it's always
set.

[sakal, 2017/03/10 11:23:13]

Done.

     [_client setMaxBitrate:[settingsModel currentMaxBitrateSettingFromStore]];
     [_client setCameraConstraints:cameraConstraints];
     [_client connectToRoomWithId:room