Add embedder-specific headers to HTTP CONNECT tunnel request

net/http/http_proxy_client_socket.h

Index: net/http/http_proxy_client_socket.h
diff --git a/net/http/http_proxy_client_socket.h b/net/http/http_proxy_client_socket.h
index a2682c505b111792d9a4f07cc5f7657023e93765..0dc49cf13b524198f89fa7f46a3b25233bfff670 100644
--- a/net/http/http_proxy_client_socket.h
+++ b/net/http/http_proxy_client_socket.h
@@ -8,6 +8,7 @@
 #include <string>
 
 #include "base/basictypes.h"
+#include "base/callback.h"
 #include "base/memory/ref_counted.h"
 #include "net/base/completion_callback.h"
 #include "net/base/host_port_pair.h"
@@ -47,6 +48,9 @@ class HttpProxyClientSocket : public ProxyClientSocket {
                         bool tunnel,
                         bool using_spdy,
                         NextProto protocol_negotiated,
+                        const base::Callback<void(
+                            const HostPortPair&, HttpRequestHeaders*)>&
+                                before_proxy_tunnel_request_callback,
                         bool is_https_proxy);
 
   // On destruction Disconnect() is called.
@@ -163,6 +167,10 @@ class HttpProxyClientSocket : public ProxyClientSocket {
   bool redirect_has_load_timing_info_;
   LoadTimingInfo redirect_load_timing_info_;
 
+  const HostPortPair proxy_server_;
+  base::Callback<void(const HostPortPair&, HttpRequestHeaders*)>
+      before_proxy_tunnel_request_callback_;
+
   const BoundNetLog net_log_;
 
   DISALLOW_COPY_AND_ASSIGN(HttpProxyClientSocket);