Update API for Objective-C RTCPeerConnection.

BUG=

Review URL: https://codereview.webrtc.org/1640993002

Cr-Commit-Position: refs/heads/master@{#11590}
diff --git a/webrtc/api/api.gyp b/webrtc/api/api.gyp
index fe7cd0e..1efd531 100644
--- a/webrtc/api/api.gyp
+++ b/webrtc/api/api.gyp
@@ -176,6 +176,11 @@
             'objc/RTCMediaStreamTrack.mm',
             'objc/RTCOpenGLVideoRenderer.h',
             'objc/RTCOpenGLVideoRenderer.mm',
+            'objc/RTCPeerConnection+DataChannel.mm',
+            'objc/RTCPeerConnection+Private.h',
+            'objc/RTCPeerConnection+Stats.mm',
+            'objc/RTCPeerConnection.h',
+            'objc/RTCPeerConnection.mm',
             'objc/RTCPeerConnectionFactory+Private.h',
             'objc/RTCPeerConnectionFactory.h',
             'objc/RTCPeerConnectionFactory.mm',