Support building WebRTC without audio and video for IOS

webrtc/sdk/objc/Framework/Classes/PeerConnection/RTCPeerConnectionFactory.mm

Index: webrtc/sdk/objc/Framework/Classes/PeerConnection/RTCPeerConnectionFactory.mm
diff --git a/webrtc/sdk/objc/Framework/Classes/PeerConnection/RTCPeerConnectionFactory.mm b/webrtc/sdk/objc/Framework/Classes/PeerConnection/RTCPeerConnectionFactory.mm
index a883587af26516979507fec961502d6229453560..7145e1d18d86c3c5deeca7f88556b0a0a135680c 100644
--- a/webrtc/sdk/objc/Framework/Classes/PeerConnection/RTCPeerConnectionFactory.mm
+++ b/webrtc/sdk/objc/Framework/Classes/PeerConnection/RTCPeerConnectionFactory.mm
@@ -24,6 +24,10 @@
 #include "Video/objcvideotracksource.h"
 #include "VideoToolbox/videocodecfactory.h"
 #include "webrtc/api/videosourceproxy.h"
+// Adding the nogncheck to disable the including header check.
+// The no-media version PeerConnectionFactory doesn't depend on media related C++ target.

[tommi, 2017/06/28 15:06:45]

please run |git cl format|

[Zhi Huang, 2017/06/28 19:47:10]

This is what I got after git cl format. It seems that the style guide are
different for objc file. The column limitation is 100.
But I can manually make it 80 since this is c++ code.

+// TODO(zhihuang): Remove nogncheck once MediaEngineInterface is moved to C++ API layer.
+#include "webrtc/media/engine/webrtcmediaengine.h"  // nogncheck
 
 @implementation RTCPeerConnectionFactory {
   std::unique_ptr<rtc::Thread> _networkThread;
@@ -47,7 +51,21 @@
     _signalingThread = rtc::Thread::Create();
     result = _signalingThread->Start();
     NSAssert(result, @"Failed to start signaling thread.");
-
+#ifdef HAVE_NO_MEDIA
+    _nativeFactory = webrtc::CreateModularPeerConnectionFactory(
+        _networkThread.get(),
+        _workerThread.get(),
+        _signalingThread.get(),
+        nullptr /*default_adm*/,

[tommi, 2017/06/28 15:06:45]

can we use // comment style?

nullptr,  // default_adm
(etc)

[Zhi Huang, 2017/06/28 19:47:10]

Yeah, sure. Done.

+        nullptr /*audio_encoder_factory*/,
+        nullptr /*audio_decoder_factory*/,
+        nullptr /*video_encoder_factory*/,
+        nullptr /*video_decoder_factory*/,
+        nullptr /*audio_mixer*/,
+        std::unique_ptr<cricket::MediaEngineInterface>(),
+        std::unique_ptr<webrtc::CallFactoryInterface>(),
+        std::unique_ptr<webrtc::RtcEventLogFactoryInterface>());
+#else
     const auto encoder_factory = new webrtc::VideoToolboxVideoEncoderFactory();
     const auto decoder_factory = new webrtc::VideoToolboxVideoDecoderFactory();
 
@@ -56,6 +74,7 @@
     _nativeFactory = webrtc::CreatePeerConnectionFactory(
         _networkThread.get(), _workerThread.get(), _signalingThread.get(),
         nullptr, encoder_factory, decoder_factory);
+#endif
     NSAssert(_nativeFactory, @"Failed to initialize PeerConnectionFactory!");
   }
   return self;
@@ -85,8 +104,11 @@
 
 - (RTCAVFoundationVideoSource *)avFoundationVideoSourceWithConstraints:
     (nullable RTCMediaConstraints *)constraints {
-  return [[RTCAVFoundationVideoSource alloc] initWithFactory:self
-                                                 constraints:constraints];
+#ifdef HAVE_NO_MEDIA
+  return nil;
+#else
+  return [[RTCAVFoundationVideoSource alloc] initWithFactory:self constraints:constraints];
+#endif
 }
 
 - (RTCVideoSource *)videoSource {