Allows deferral of a URLRequest just before talking to the network, at

net/http/http_network_transaction.h

Index: net/http/http_network_transaction.h
diff --git a/net/http/http_network_transaction.h b/net/http/http_network_transaction.h
index 10436b63c821223e1accb440655d1465715e81ca..d2716c1fd8c42edb076b9053a0dca2361c86c885 100644
--- a/net/http/http_network_transaction.h
+++ b/net/http/http_network_transaction.h
@@ -72,6 +72,9 @@ class NET_EXPORT_PRIVATE HttpNetworkTransaction
   virtual void SetPriority(RequestPriority priority) OVERRIDE;
   virtual void SetWebSocketHandshakeStreamCreateHelper(
       WebSocketHandshakeStreamBase::CreateHelper* create_helper) OVERRIDE;
+  virtual void SetBeforeNetworkStartCallback(
+      const base::Callback<void(bool*)>& callback) OVERRIDE;
+  virtual int ResumeNetworkStart() OVERRIDE;
 
   // HttpStreamRequest::Delegate methods:
   virtual void OnStreamReady(const SSLConfig& used_ssl_config,
@@ -117,6 +120,7 @@ class NET_EXPORT_PRIVATE HttpNetworkTransaction
                            FlowControlNegativeSendWindowSize);
 
   enum State {
+    STATE_NOTIFY_BEFORE_CREATE_STREAM,
     STATE_CREATE_STREAM,
     STATE_CREATE_STREAM_COMPLETE,
     STATE_INIT_STREAM,
@@ -152,6 +156,7 @@ class NET_EXPORT_PRIVATE HttpNetworkTransaction
   // argument receive the result from the previous state.  If a method returns
   // ERR_IO_PENDING, then the result from OnIOComplete will be passed to the
   // next state method as the result arg.
+  int DoNotifyBeforeCreateStream();
   int DoCreateStream();
   int DoCreateStreamComplete(int result);
   int DoInitStream();
@@ -332,6 +337,8 @@ class NET_EXPORT_PRIVATE HttpNetworkTransaction
   WebSocketHandshakeStreamBase::CreateHelper*
       websocket_handshake_stream_base_create_helper_;
 
+  base::Callback<void(bool*)> before_network_start_callback_;
+
   DISALLOW_COPY_AND_ASSIGN(HttpNetworkTransaction);
 };