make SetReceiveBufferSize and SetSendBufferSize return net error codes (instead of bools)

net/base/net_errors.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef NET_BASE_NET_ERRORS_H__
 #define NET_BASE_NET_ERRORS_H__
 
 #include <vector>
 
 #include "base/basictypes.h"
@@ skipping 39 matching lines @@
 // an action that is represented as a net error code.
 //
 // Note that the error codes are all positive (since histograms expect positive
 // sample values). Also note that a guard bucket is created after any valid
 // error code that is not followed immediately by a valid error code.
 NET_EXPORT std::vector<int> GetAllErrorCodesForUma();
 
 // A convenient function to translate file error to net error code.
 NET_EXPORT Error FileErrorToNetError(base::File::Error file_error);
 
+// Return a net_error other than net::OK, based on |os_error|.
+// Some older OSs (Mac 10.6?) may fail to set the os_error properly, even when
+// a system function returns a failing value.  This function is used to map such
+// cases into a default net_error, if the net_error would otherwise mistakenly
+// report OK (such as when errno was zero).
+int MapSystemErrorWithDefault(int os_error, int default_net_error);

[wtc, 2014/04/09 15:34:49]

Nit: please list this function right below the closely related MapSystemError.

+
 }  // namespace net
 
 #endif  // NET_BASE_NET_ERRORS_H__