Plumbing for TCP FastOpen for SSL sockets.

net/socket/tcp_socket.h

Index: net/socket/tcp_socket.h
diff --git a/net/socket/tcp_socket.h b/net/socket/tcp_socket.h
index 8b36fade758e05db222d9fa4e2ee739e110b2779..702d8f413d75c2a08aa1701d92ada9d3f1e845d2 100644
--- a/net/socket/tcp_socket.h
+++ b/net/socket/tcp_socket.h
@@ -16,13 +16,17 @@
 
 namespace net {
 
-// Enable/disable experimental TCP FastOpen option.
-// Not thread safe.  Must be called during initialization/startup only.
-NET_EXPORT void SetTCPFastOpenEnabled(bool value);
+// Check if TCP FastOpen option is supported by the OS.
+bool IsTCPFastOpenSupported();
 
-// Check if the TCP FastOpen option is enabled.
+// Check if TCP FastOpen option is enabled.
 bool IsTCPFastOpenEnabled();
 
+// Checks if TCP FastOpen is supported by the kernel. Also enables TFO for all
+// connections if indicated by user.
+// Not thread safe.  Must be called during initialization/startup only.
+NET_EXPORT void CheckSupportAndMaybeEnableTCPFastOpen(bool user_enabled_tfo);

[mmenke, 2014/08/12 15:25:15]

Per earlier comment, "tfo" isn't a standard abbreviation, so should use
something else, either fast_open, or tcp_fast_open... Or just enabled_by_user or
something.

[mmenke, 2014/08/12 15:25:15]

Calling this with false does not indicate to me "Enable this for SSL only if
supported, if passed in false."

[Jana, 2014/08/13 07:33:40]

Changed, PTAL. The initial intent was to indicate "Enable this for all
connections if true is passed in." I hope the new signaling is better ... if
not, please feel free to suggest something better.

[Jana, 2014/08/13 07:33:40]

Done.

+
 // TCPSocket provides a platform-independent interface for TCP sockets.
 //
 // It is recommended to use TCPClientSocket/TCPServerSocket instead of this