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..273d4ff8d167dc70e5ab2e6307e0d3b8cd6673d9 100644
--- a/webrtc/sdk/objc/Framework/Classes/PeerConnection/RTCPeerConnectionFactory.mm
+++ b/webrtc/sdk/objc/Framework/Classes/PeerConnection/RTCPeerConnectionFactory.mm
@@ -25,40 +25,18 @@
 #include "VideoToolbox/videocodecfactory.h"
 #include "webrtc/api/videosourceproxy.h"
 
-@implementation RTCPeerConnectionFactory {
-  std::unique_ptr<rtc::Thread> _networkThread;
-  std::unique_ptr<rtc::Thread> _workerThread;
-  std::unique_ptr<rtc::Thread> _signalingThread;
-  BOOL _hasStartedAecDump;
-}
+@implementation RTCPeerConnectionFactory
 
 @synthesize nativeFactory = _nativeFactory;
 
-- (instancetype)init {
-  if ((self = [super init])) {
-    _networkThread = rtc::Thread::CreateWithSocketServer();
-    BOOL result = _networkThread->Start();
-    NSAssert(result, @"Failed to start network thread.");
-
-    _workerThread = rtc::Thread::Create();
-    result = _workerThread->Start();
-    NSAssert(result, @"Failed to start worker thread.");
-
-    _signalingThread = rtc::Thread::Create();
-    result = _signalingThread->Start();
-    NSAssert(result, @"Failed to start signaling thread.");
-
-    const auto encoder_factory = new webrtc::VideoToolboxVideoEncoderFactory();
-    const auto decoder_factory = new webrtc::VideoToolboxVideoDecoderFactory();
-
-    // Ownership of encoder/decoder factories is passed on to the
-    // peerconnectionfactory, that handles deleting them.
-    _nativeFactory = webrtc::CreatePeerConnectionFactory(
-        _networkThread.get(), _workerThread.get(), _signalingThread.get(),
-        nullptr, encoder_factory, decoder_factory);
-    NSAssert(_nativeFactory, @"Failed to initialize PeerConnectionFactory!");
-  }
-  return self;
+- (RTCPeerConnection *)peerConnectionWithConfiguration:(RTCConfiguration *)configuration
+                                           constraints:(RTCMediaConstraints *)constraints
+                                              delegate:
+                                                  (nullable id<RTCPeerConnectionDelegate>)delegate {
+  return [[RTCPeerConnection alloc] initWithFactory:self
+                                      configuration:configuration
+                                        constraints:constraints
+                                           delegate:delegate];
 }
 
 - (RTCAudioSource *)audioSourceWithConstraints:(nullable RTCMediaConstraints *)constraints {
@@ -76,50 +54,8 @@
   return [self audioTrackWithSource:audioSource trackId:trackId];
 }
 
-- (RTCAudioTrack *)audioTrackWithSource:(RTCAudioSource *)source
-                                trackId:(NSString *)trackId {
-  return [[RTCAudioTrack alloc] initWithFactory:self
-                                         source:source
-                                        trackId:trackId];
-}
-
-- (RTCAVFoundationVideoSource *)avFoundationVideoSourceWithConstraints:
-    (nullable RTCMediaConstraints *)constraints {
-  return [[RTCAVFoundationVideoSource alloc] initWithFactory:self
-                                                 constraints:constraints];
-}
-
-- (RTCVideoSource *)videoSource {
-  rtc::scoped_refptr<webrtc::ObjcVideoTrackSource> objcVideoTrackSource(
-      new rtc::RefCountedObject<webrtc::ObjcVideoTrackSource>());
-  return [[RTCVideoSource alloc]
-      initWithNativeVideoSource:webrtc::VideoTrackSourceProxy::Create(_signalingThread.get(),
-                                                                      _workerThread.get(),
-                                                                      objcVideoTrackSource)];
-}
-
-- (RTCVideoTrack *)videoTrackWithSource:(RTCVideoSource *)source
-                                trackId:(NSString *)trackId {
-  return [[RTCVideoTrack alloc] initWithFactory:self
-                                         source:source
-                                        trackId:trackId];
-}
-
-- (RTCMediaStream *)mediaStreamWithStreamId:(NSString *)streamId {
-  return [[RTCMediaStream alloc] initWithFactory:self
-                                        streamId:streamId];
-}
-
-- (RTCPeerConnection *)peerConnectionWithConfiguration:
-    (RTCConfiguration *)configuration
-                                           constraints:
-    (RTCMediaConstraints *)constraints
-                                              delegate:
-    (nullable id<RTCPeerConnectionDelegate>)delegate {
-  return [[RTCPeerConnection alloc] initWithFactory:self
-                                      configuration:configuration
-                                        constraints:constraints
-                                           delegate:delegate];
+- (RTCAudioTrack *)audioTrackWithSource:(RTCAudioSource *)source trackId:(NSString *)trackId {
+  return [[RTCAudioTrack alloc] initWithFactory:self source:source trackId:trackId];
 }
 
 - (BOOL)startAecDumpWithFilePath:(NSString *)filePath