Implement zero-copy SSL buffers.

net/socket/ssl_client_socket_openssl.h

Index: net/socket/ssl_client_socket_openssl.h
diff --git a/net/socket/ssl_client_socket_openssl.h b/net/socket/ssl_client_socket_openssl.h
index 6343cb7493842647fc25384a4b348eb0a6bea10d..6aaf1e16672d65dc753da56ded07c2e90f546a34 100644
--- a/net/socket/ssl_client_socket_openssl.h
+++ b/net/socket/ssl_client_socket_openssl.h
@@ -187,8 +187,10 @@ class SSLClientSocketOpenSSL : public SSLClientSocket {
   bool transport_send_busy_;
   bool transport_recv_busy_;
 
-  scoped_refptr<DrainableIOBuffer> send_buffer_;
-  scoped_refptr<IOBuffer> recv_buffer_;
+  // Buffers which are shared by BoringSSL and SSLClientSocketOpenSSL.
+  // GrowableIOBuffer is used to keep ownership and setting offset.

[agl, 2014/12/17 19:12:22]

// GrowableIOBuffer is used to keep ownership and for setting offsets.

+  scoped_refptr<GrowableIOBuffer> send_buffer_;

[agl, 2014/12/17 19:12:22]

I'm not sure that a growable IOBuffer is needed here because it never grows by
the looks of things. Can a simple IOBuffer be used? Setting the offset is only
done just before use, so a simple addition of the offset could replace that.

[haavardm, 2014/12/17 22:04:53]

I used GrowableIOBuffer just for the set offset function (hence the comment). An
alternative is DrainableIOBuffer. Might that one is better suited for this (I
would only use the offset anyway, but the naming might be better)

I'm not sure I see how I can change the offset using the simple IOBuffer. I
can't create a new IOBuffer for each send (that would allocate memory) and
socket->Read needs an IOBuffer that returns the offset buffer when Data() is
called. Also I cannot use the wrapped buffer, as that leaves the socket without
a reference/ownership to the data.

[agl, 2014/12/17 22:29:57]

Thanks. It was the socket->Read requirement that I missed.

+  scoped_refptr<GrowableIOBuffer> recv_buffer_;
 
   CompletionCallback user_connect_callback_;
   CompletionCallback user_read_callback_;