iOS: unbreak the build following r4546

BUG=2255
R=niklas.enbom@webrtc.org, sjlee@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/2078004

git-svn-id: http://webrtc.googlecode.com/svn/trunk@4577 4adac7df-926f-26a2-2b94-8c16560cd09d
diff --git a/talk/examples/ios/AppRTCDemo/APPRTCAppClient.m b/talk/examples/ios/AppRTCDemo/APPRTCAppClient.m
index 93f0d36..93f693f 100644
--- a/talk/examples/ios/AppRTCDemo/APPRTCAppClient.m
+++ b/talk/examples/ios/AppRTCDemo/APPRTCAppClient.m
@@ -34,7 +34,7 @@
 
 @interface APPRTCAppClient ()
 
-@property(nonatomic, assign) dispatch_queue_t backgroundQueue;
+@property(nonatomic, strong) dispatch_queue_t backgroundQueue;
 @property(nonatomic, copy) NSString *baseURL;
 @property(nonatomic, strong) GAEChannelClient *gaeChannel;
 @property(nonatomic, copy) NSString *postMessageUrl;
@@ -52,7 +52,6 @@
 - (id)init {
   if (self = [super init]) {
     _backgroundQueue = dispatch_queue_create("RTCBackgroundQueue", NULL);
-    dispatch_retain(_backgroundQueue);
     _sendQueue = [NSMutableArray array];
     // Uncomment to see Request/Response logging.
     // _verboseLogging = YES;
@@ -60,10 +59,6 @@
   return self;
 }
 
-- (void)dealloc {
-  dispatch_release(_backgroundQueue);
-}
-
 #pragma mark - Public methods
 
 - (void)connectToRoom:(NSURL *)url {