Update API for Objective-C RTCMediaStream.

BUG=
R=tkchin@webrtc.org

Review URL: https://codereview.webrtc.org/1558733002 .

Patch from Jon Hjelle <hjon@andyet.net>.

Cr-Commit-Position: refs/heads/master@{#11351}
diff --git a/webrtc/api/api.gyp b/webrtc/api/api.gyp
index 5d40cd0..5f848d7 100644
--- a/webrtc/api/api.gyp
+++ b/webrtc/api/api.gyp
@@ -19,12 +19,12 @@
             '../../talk/libjingle.gyp:libjingle_peerconnection',
           ],
           'sources': [
-            'objc/RTCAudioTrack+Private.h',
-            'objc/RTCAudioTrack.h',
-            'objc/RTCAudioTrack.mm',
             'objc/RTCAVFoundationVideoSource+Private.h',
             'objc/RTCAVFoundationVideoSource.h',
             'objc/RTCAVFoundationVideoSource.mm',
+            'objc/RTCAudioTrack+Private.h',
+            'objc/RTCAudioTrack.h',
+            'objc/RTCAudioTrack.mm',
             'objc/RTCIceCandidate+Private.h',
             'objc/RTCIceCandidate.h',
             'objc/RTCIceCandidate.mm',
@@ -34,6 +34,9 @@
             'objc/RTCMediaConstraints+Private.h',
             'objc/RTCMediaConstraints.h',
             'objc/RTCMediaConstraints.mm',
+            'objc/RTCMediaStream+Private.h',
+            'objc/RTCMediaStream.h',
+            'objc/RTCMediaStream.mm',
             'objc/RTCMediaStreamTrack+Private.h',
             'objc/RTCMediaStreamTrack.h',
             'objc/RTCMediaStreamTrack.mm',