Implement a 15 connection per proxy server limit.

net/proxy/proxy_server.h

 // Copyright (c) 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_PROXY_PROXY_SERVER_H_
 #define NET_PROXY_PROXY_SERVER_H_
 
 #include "build/build_config.h"
 
 #if defined(OS_MACOSX)
 #include <CoreFoundation/CoreFoundation.h>
 #endif
 
 #include <string>
+#include "net/base/host_port_pair.h"
 
 namespace net {
 
 // ProxyServer encodes the {type, host, port} of a proxy server.
 // ProxyServer is immutable.
 class ProxyServer {
  public:
   // The type of proxy. These are defined as bit flags so they can be ORed
   // together to pass as the |scheme_bit_field| argument to
   // ProxyService::RemoveProxiesWithoutScheme().
@@ skipping 33 matching lines @@
 
   // Gets the host portion of the proxy server. If the host portion is an
   // IPv6 literal address, the return value does not include the square
   // brackets ([]) used to separate it from the port portion.
   std::string HostNoBrackets() const;
 
   // Gets the port portion of the proxy server.
   int port() const;
 
   // Returns the <host>":"<port> string for the proxy server.
+  // TODO(willchan): Remove in favor of host_port_pair().
   std::string host_and_port() const;
 
+  // TODO(willchan): Change to const HostPortPair& after refactoring |host_| and
+  // |port_| here.
+  HostPortPair host_port_pair() const;
+
   // Parse from an input with format:
   //   [<scheme>"://"]<server>[":"<port>]
   //
   // Both <scheme> and <port> are optional. If <scheme> is omitted, it will be
   // assumed as |default_scheme|. If <port> is omitted, it will be assumed as
   // the default port for the chosen scheme (80 for "http", 1080 for "socks").
   //
   // If parsing fails the instance will be set to invalid.
   //
   // Examples (for |default_scheme| = SCHEME_HTTP ):
@@ skipping 67 matching lines @@
       std::string::const_iterator host_and_port_end);
 
   Scheme scheme_;
   std::string host_;
   int port_;
 };
 
 }  // namespace net
 
 #endif  // NET_PROXY_PROXY_SERVER_H_