Add video codec setting to AppRTCMobile on iOS.

List items in settings menu no longer stay selected. Checkmarks are now
added to the selected options before the view appears.

BUG=webrtc:7316
TBR=denicija

Review-Url: https://codereview.webrtc.org/2735303004
Cr-Commit-Position: refs/heads/master@{#17296}
diff --git a/webrtc/examples/objc/AppRTCMobile/ios/ARDSettingsModel.h b/webrtc/examples/objc/AppRTCMobile/ios/ARDSettingsModel.h
index 602a464..0eb7b31 100644
--- a/webrtc/examples/objc/AppRTCMobile/ios/ARDSettingsModel.h
+++ b/webrtc/examples/objc/AppRTCMobile/ios/ARDSettingsModel.h
@@ -49,6 +49,26 @@
 - (BOOL)storeVideoResoultionConstraint:(NSString *)constraint;
 
 /**
+ * Returns array of available video codecs.
+ */
+- (NSArray<NSString *> *)availableVideoCodecs;
+
+/**
+ * Returns current video codec setting from store if present.
+ */
+- (NSString *)currentVideoCodecSettingFromStore;
+
+/**
+ * Stores the provided video codec setting into the store.
+ *
+ * If the provided constraint is not part of the available video codecs
+ * the store operation will not be executed and NO will be returned.
+ * @param video codec settings the string to be stored.
+ * @return YES/NO depending on success.
+ */
+- (BOOL)storeVideoCodecSetting:(NSString *)videoCodec;
+
+/**
  * Converts the current media constraints from store into dictionary with RTCMediaConstraints
  * values.
  *