Objective-C readability review.

BUG=
R=rsesek@chromium.org

Review URL: https://webrtc-codereview.appspot.com/34679004

Cr-Commit-Position: refs/heads/master@{#8784}
git-svn-id: http://webrtc.googlecode.com/svn/trunk@8784 4adac7df-926f-26a2-2b94-8c16560cd09d
diff --git a/talk/examples/objc/AppRTCDemo/ARDAppClient.h b/talk/examples/objc/AppRTCDemo/ARDAppClient.h
index 94077f2..b88b570 100644
--- a/talk/examples/objc/AppRTCDemo/ARDAppClient.h
+++ b/talk/examples/objc/AppRTCDemo/ARDAppClient.h
@@ -39,6 +39,8 @@
 };
 
 @class ARDAppClient;
+// The delegate is informed of pertinent events and will be called on the
+// main queue.
 @protocol ARDAppClientDelegate <NSObject>
 
 - (void)appClient:(ARDAppClient *)client
@@ -58,12 +60,15 @@
 
 @end
 
-// Handles connections to the AppRTC server for a given room.
+// Handles connections to the AppRTC server for a given room. Methods on this
+// class should only be called from the main queue.
 @interface ARDAppClient : NSObject
 
 @property(nonatomic, readonly) ARDAppClientState state;
 @property(nonatomic, weak) id<ARDAppClientDelegate> delegate;
 
+// Convenience constructor since all expected use cases will need a delegate
+// in order to receive remote tracks.
 - (instancetype)initWithDelegate:(id<ARDAppClientDelegate>)delegate;
 
 // Establishes a connection with the AppRTC servers for the given room id.