Replace scoped_ptr with unique_ptr in webrtc/p2p/

But keep #including scoped_ptr.h in .h files, so as not to break
WebRTC users who expect those .h files to give them rtc::scoped_ptr.

BUG=webrtc:5520

Review URL: https://codereview.webrtc.org/1923163003

Cr-Commit-Position: refs/heads/master@{#12532}
diff --git a/webrtc/p2p/base/asyncstuntcpsocket_unittest.cc b/webrtc/p2p/base/asyncstuntcpsocket_unittest.cc
index 22c1b26..5929d1f 100644
--- a/webrtc/p2p/base/asyncstuntcpsocket_unittest.cc
+++ b/webrtc/p2p/base/asyncstuntcpsocket_unittest.cc
@@ -8,6 +8,8 @@
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
+#include <memory>
+
 #include "webrtc/p2p/base/asyncstuntcpsocket.h"
 #include "webrtc/base/asyncsocket.h"
 #include "webrtc/base/gunit.h"
@@ -122,11 +124,11 @@
     return ret;
   }
 
-  rtc::scoped_ptr<rtc::VirtualSocketServer> vss_;
+  std::unique_ptr<rtc::VirtualSocketServer> vss_;
   rtc::SocketServerScope ss_scope_;
-  rtc::scoped_ptr<AsyncStunTCPSocket> send_socket_;
-  rtc::scoped_ptr<AsyncStunTCPSocket> recv_socket_;
-  rtc::scoped_ptr<rtc::AsyncPacketSocket> listen_socket_;
+  std::unique_ptr<AsyncStunTCPSocket> send_socket_;
+  std::unique_ptr<AsyncStunTCPSocket> recv_socket_;
+  std::unique_ptr<rtc::AsyncPacketSocket> listen_socket_;
   std::list<std::string> recv_packets_;
 };