Immediately reject empty cookie headers.

net/http/http_response_headers.h

 // Copyright (c) 2006-2009 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_HTTP_HTTP_RESPONSE_HEADERS_H_
 #define NET_HTTP_HTTP_RESPONSE_HEADERS_H_
 #pragma once
 
 #include <string>
 #include <vector>
@@ skipping 120 matching lines @@
   }
 
   // Get the HTTP status text of the normalized status line.
   std::string GetStatusText() const;
 
   // Enumerate the "lines" of the response headers.  This skips over the status
   // line.  Use GetStatusLine if you are interested in that.  Note that this
   // method returns the un-coalesced response header lines, so if a response
   // header appears on multiple lines, then it will appear multiple times in
   // this enumeration (in the order the header lines were received from the
-  // server).  Initialize a 'void*' variable to NULL and pass it by address to
-  // EnumerateHeaderLines.  Call EnumerateHeaderLines repeatedly until it
-  // returns false.  The out-params 'name' and 'value' are set upon success.
+  // server).  Also, a given header might have an empty value.  Initialize a
+  // 'void*' variable to NULL and pass it by address to EnumerateHeaderLines.
+  // Call EnumerateHeaderLines repeatedly until it returns false.  The
+  // out-params 'name' and 'value' are set upon success.
   bool EnumerateHeaderLines(void** iter,
                             std::string* name,
                             std::string* value) const;
 
   // Enumerate the values of the specified header.   If you are only interested
   // in the first header, then you can pass NULL for the 'iter' parameter.
   // Otherwise, to iterate across all values for the specified header,
   // initialize a 'void*' variable to NULL and pass it by address to
-  // EnumerateHeader.  Call EnumerateHeader repeatedly until it returns false.
+  // EnumerateHeader. Note that a header might have an empty value. Call
+  // EnumerateHeader repeatedly until it returns false.
   bool EnumerateHeader(void** iter,
                        const std::string& name,
                        std::string* value) const;
 
   // Returns true if the response contains the specified header-value pair.
   // Both name and value are compared case insensitively.
   bool HasHeaderValue(const std::string& name, const std::string& value) const;
 
   // Returns true if the response contains the specified header.
   // The name is compared case insensitively.
@@ skipping 187 matching lines @@
 
   // The parsed http version number (not normalized).
   HttpVersion parsed_http_version_;
 
   DISALLOW_COPY_AND_ASSIGN(HttpResponseHeaders);
 };
 
 }  // namespace net
 
 #endif  // NET_HTTP_HTTP_RESPONSE_HEADERS_H_