Replace NULL with nullptr or null in webrtc/base/.

webrtc/base/proxyserver.cc

Index: webrtc/base/proxyserver.cc
diff --git a/webrtc/base/proxyserver.cc b/webrtc/base/proxyserver.cc
index 66cf695755e415613d65452d0166dc842582427c..713a98679a0cc3a0e36c46807c7408e3f5cb47b3 100644
--- a/webrtc/base/proxyserver.cc
+++ b/webrtc/base/proxyserver.cc
@@ -24,7 +24,7 @@ ProxyServer::ProxyServer(
     : ext_factory_(ext_factory), ext_ip_(ext_ip.ipaddr(), 0),  // strip off port
       server_socket_(int_factory->CreateAsyncSocket(int_addr.family(),
                                                     SOCK_STREAM)) {
-  RTC_DCHECK(server_socket_.get() != NULL);
+  RTC_DCHECK(server_socket_.get() != nullptr);
   RTC_DCHECK(int_addr.family() == AF_INET || int_addr.family() == AF_INET6);
   server_socket_->Bind(int_addr);
   server_socket_->Listen(5);
@@ -43,8 +43,8 @@ SocketAddress ProxyServer::GetServerAddress() {
 }
 
 void ProxyServer::OnAcceptEvent(AsyncSocket* socket) {
-  RTC_DCHECK(socket != NULL && socket == server_socket_.get());
-  AsyncSocket* int_socket = socket->Accept(NULL);
+  RTC_DCHECK(socket != nullptr && socket == server_socket_.get());
+  AsyncSocket* int_socket = socket->Accept(nullptr);
   AsyncProxyServerSocket* wrapped_socket = WrapSocket(int_socket);
   AsyncSocket* ext_socket = ext_factory_->CreateAsyncSocket(ext_ip_.family(),
                                                             SOCK_STREAM);
@@ -84,7 +84,7 @@ ProxyBinding::~ProxyBinding() = default;
 
 void ProxyBinding::OnConnectRequest(AsyncProxyServerSocket* socket,
                                    const SocketAddress& addr) {
-  RTC_DCHECK(!connected_ && ext_socket_.get() != NULL);
+  RTC_DCHECK(!connected_ && ext_socket_.get() != nullptr);
   ext_socket_->Connect(addr);
   // TODO: handle errors here
 }
@@ -103,7 +103,7 @@ void ProxyBinding::OnInternalClose(AsyncSocket* socket, int err) {
 }
 
 void ProxyBinding::OnExternalConnect(AsyncSocket* socket) {
-  RTC_DCHECK(socket != NULL);
+  RTC_DCHECK(socket != nullptr);
   connected_ = true;
   int_socket_->SendConnectResult(0, socket->GetRemoteAddress());
 }
@@ -126,7 +126,7 @@ void ProxyBinding::OnExternalClose(AsyncSocket* socket, int err) {
 
 void ProxyBinding::Read(AsyncSocket* socket, FifoBuffer* buffer) {
   // Only read if the buffer is empty.
-  RTC_DCHECK(socket != NULL);
+  RTC_DCHECK(socket != nullptr);
   size_t size;
   int read;
   if (buffer->GetBuffered(&size) && size == 0) {
@@ -137,7 +137,7 @@ void ProxyBinding::Read(AsyncSocket* socket, FifoBuffer* buffer) {
 }
 
 void ProxyBinding::Write(AsyncSocket* socket, FifoBuffer* buffer) {
-  RTC_DCHECK(socket != NULL);
+  RTC_DCHECK(socket != nullptr);
   size_t size;
   int written;
   const void* p = buffer->GetReadData(&size);