Extracting NetLog inner classes into their own classes.

media/cast/test/utility/net_utility.cc

Index: media/cast/test/utility/net_utility.cc
diff --git a/media/cast/test/utility/net_utility.cc b/media/cast/test/utility/net_utility.cc
index 9a1457bb377e65b926c7963979b0e8320d23c0af..913f862e03d406c33f351c8a9ca6ee06e0dda708 100644
--- a/media/cast/test/utility/net_utility.cc
+++ b/media/cast/test/utility/net_utility.cc
@@ -8,6 +8,7 @@
 
 #include "net/base/ip_address.h"
 #include "net/base/net_errors.h"
+#include "net/log/net_log_source.h"
 #include "net/udp/udp_server_socket.h"
 
 namespace media {
@@ -17,7 +18,7 @@ namespace test {
 // TODO(hubbe): Move to /net/.
 net::IPEndPoint GetFreeLocalPort() {
   std::unique_ptr<net::UDPServerSocket> receive_socket(
-      new net::UDPServerSocket(NULL, net::NetLog::Source()));
+      new net::UDPServerSocket(NULL, net::NetLogSource()));
   receive_socket->AllowAddressReuse();
   CHECK_EQ(net::OK, receive_socket->Listen(
                         net::IPEndPoint(net::IPAddress::IPv4Localhost(), 0)));