Fix size_t truncations in net for 64-bit VS 2015

net/socket/socks5_client_socket_unittest.cc

Index: net/socket/socks5_client_socket_unittest.cc
diff --git a/net/socket/socks5_client_socket_unittest.cc b/net/socket/socks5_client_socket_unittest.cc
index 76146c7ab83e959bc4998e18cc2ab10412789a83..5fa5bf8e0784993ad831e200c418754d9d4265d7 100644
--- a/net/socket/socks5_client_socket_unittest.cc
+++ b/net/socket/socks5_client_socket_unittest.cc
@@ -194,7 +194,7 @@ TEST_F(SOCKS5ClientSocketTest, ConnectAndDisconnectTwice) {
   };
 
   std::string request(kSOCKS5DomainRequest, arraysize(kSOCKS5DomainRequest));
-  request.push_back(hostname.size());
+  request.push_back(static_cast<char>(hostname.size()));
   request.append(hostname);
   request.append(reinterpret_cast<const char*>(&kNwPort), sizeof(kNwPort));