Add iOS static library GN build script.

webrtc/sdk/objc/Framework/Classes/RTCVideoTrack.mm

Index: webrtc/sdk/objc/Framework/Classes/RTCVideoTrack.mm
diff --git a/webrtc/sdk/objc/Framework/Classes/RTCVideoTrack.mm b/webrtc/sdk/objc/Framework/Classes/RTCVideoTrack.mm
index 6691375fbffb9ec601c598bd37448a69b7561627..9fa61114115a9f1a14d0b0e62f13c09145846c0a 100644
--- a/webrtc/sdk/objc/Framework/Classes/RTCVideoTrack.mm
+++ b/webrtc/sdk/objc/Framework/Classes/RTCVideoTrack.mm
@@ -69,9 +69,9 @@
 - (void)addRenderer:(id<RTCVideoRenderer>)renderer {
   // Make sure we don't have this renderer yet.
   for (RTCVideoRendererAdapter *adapter in _adapters) {
-    // Getting around unused variable error
-    if (adapter.videoRenderer != renderer) {
+    if (adapter.videoRenderer == renderer) {

[kthelgason, 2016/10/05 07:46:24]

This seems strange. Is this a bug that you're fixing? Seems unrelated to this
CL.

[tkchin_webrtc, 2016/10/05 16:42:26]

See other comment.

       NSAssert(NO, @"|renderer| is already attached to this track");
+      return;
     }
   }
   // Create a wrapper that provides a native pointer for us.