Delete deprecated PeerConnection methods, and corresponding using declarations.

webrtc/pc/test/peerconnectiontestwrapper.h

Index: webrtc/pc/test/peerconnectiontestwrapper.h
diff --git a/webrtc/pc/test/peerconnectiontestwrapper.h b/webrtc/pc/test/peerconnectiontestwrapper.h
index b761b05fcd0b9361409b8176d17debfb8793b95e..6b7fd5e95b7568d20a184cb31394bb79cb92099c 100644
--- a/webrtc/pc/test/peerconnectiontestwrapper.h
+++ b/webrtc/pc/test/peerconnectiontestwrapper.h
@@ -24,13 +24,6 @@ class PeerConnectionTestWrapper
       public webrtc::CreateSessionDescriptionObserver,
       public sigslot::has_slots<> {
  public:
-  // We need these using declarations because there are two versions of each of
-  // the below methods and we only override one of them.
-  // TODO(deadbeef): Remove once there's only one version of the methods.
-  using PeerConnectionObserver::OnAddStream;
-  using PeerConnectionObserver::OnRemoveStream;
-  using PeerConnectionObserver::OnDataChannel;
-
   static void Connect(PeerConnectionTestWrapper* caller,
                       PeerConnectionTestWrapper* callee);