Rename BEGIN_PROXY_MAP --> BEGIN_SIGNALLING_PROXY_MAP.

webrtc/api/peerconnectionfactory.cc

Index: webrtc/api/peerconnectionfactory.cc
diff --git a/webrtc/api/peerconnectionfactory.cc b/webrtc/api/peerconnectionfactory.cc
index c3c120ce7a691799f35eb5e28c1d3fd8b636e971..2a5c1777a093735c4573496fc7dbb1037c4e69d5 100644
--- a/webrtc/api/peerconnectionfactory.cc
+++ b/webrtc/api/peerconnectionfactory.cc
@@ -70,8 +70,8 @@ CreatePeerConnectionFactory() {
   if (!pc_factory->Initialize()) {
     return nullptr;
   }
-  return PeerConnectionFactoryProxy::Create(pc_factory->signaling_thread(),
-                                            pc_factory);
+  return PeerConnectionFactorySignallingProxy::Create(
+      pc_factory->signaling_thread(), pc_factory);
 }
 
 rtc::scoped_refptr<PeerConnectionFactoryInterface>
@@ -98,7 +98,8 @@ CreatePeerConnectionFactory(
   if (!result) {
     return nullptr;
   }
-  return PeerConnectionFactoryProxy::Create(signaling_thread, pc_factory);
+  return PeerConnectionFactorySignallingProxy::Create(signaling_thread,
+                                                      pc_factory);
 }
 
 PeerConnectionFactory::PeerConnectionFactory()
@@ -307,14 +308,14 @@ PeerConnectionFactory::CreatePeerConnection(
                       std::move(dtls_identity_store), observer)) {
     return nullptr;
   }
-  return PeerConnectionProxy::Create(signaling_thread(), pc);
+  return PeerConnectionSignallingProxy::Create(signaling_thread(), pc);
 }
 
 rtc::scoped_refptr<MediaStreamInterface>
 PeerConnectionFactory::CreateLocalMediaStream(const std::string& label) {
   RTC_DCHECK(signaling_thread_->IsCurrent());
-  return MediaStreamProxy::Create(signaling_thread_,
-                                  MediaStream::Create(label));
+  return MediaStreamSignallingProxy::Create(signaling_thread_,
+                                            MediaStream::Create(label));
 }
 
 rtc::scoped_refptr<VideoTrackInterface> PeerConnectionFactory::CreateVideoTrack(
@@ -331,7 +332,7 @@ PeerConnectionFactory::CreateAudioTrack(const std::string& id,
                                         AudioSourceInterface* source) {
   RTC_DCHECK(signaling_thread_->IsCurrent());
   rtc::scoped_refptr<AudioTrackInterface> track(AudioTrack::Create(id, source));
-  return AudioTrackProxy::Create(signaling_thread_, track);
+  return AudioTrackSignallingProxy::Create(signaling_thread_, track);
 }
 
 webrtc::MediaControllerInterface* PeerConnectionFactory::CreateMediaController(