Add embedder-specific headers to HTTP CONNECT tunnel request

net/http/http_network_session.h

Index: net/http/http_network_session.h
diff --git a/net/http/http_network_session.h b/net/http/http_network_session.h
index f62232a22a63982092d6560020a6be12585e5258..bf077ae8341d3011f87afdb5218e2a9fddd92af9 100644
--- a/net/http/http_network_session.h
+++ b/net/http/http_network_session.h
@@ -10,6 +10,7 @@
 #include <vector>
 
 #include "base/basictypes.h"
+#include "base/callback.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/weak_ptr.h"
 #include "base/threading/non_thread_safe.h"
@@ -120,6 +121,8 @@ class NET_EXPORT HttpNetworkSession
     QuicCryptoClientStreamFactory* quic_crypto_client_stream_factory;
     QuicVersionVector quic_supported_versions;
     QuicTagVector quic_connection_options;
+    base::Callback<void(const net::HostPortPair&, HttpRequestHeaders*)>
+        before_proxy_tunnel_request_callback;

[mef, 2014/09/02 17:08:36]

Is there particular reason why it is a separate callback and not part of say
network_delegate?

   };
 
   enum SocketPoolType {