Replace scoped_ptr with unique_ptr in webrtc/base/

This propagated into various other places. Also had to #include headers that
were implicitly pulled by "scoped_ptr.h".

BUG=webrtc:5520

Review URL: https://codereview.webrtc.org/1920043002

Cr-Commit-Position: refs/heads/master@{#12501}
diff --git a/webrtc/base/asyncudpsocket.cc b/webrtc/base/asyncudpsocket.cc
index 4e80733..7eb2a0e 100644
--- a/webrtc/base/asyncudpsocket.cc
+++ b/webrtc/base/asyncudpsocket.cc
@@ -18,7 +18,7 @@
 AsyncUDPSocket* AsyncUDPSocket::Create(
     AsyncSocket* socket,
     const SocketAddress& bind_address) {
-  scoped_ptr<AsyncSocket> owned_socket(socket);
+  std::unique_ptr<AsyncSocket> owned_socket(socket);
   if (socket->Bind(bind_address) < 0) {
     LOG(LS_ERROR) << "Bind() failed with error " << socket->GetError();
     return NULL;