Intorduce a separate preference for 'proxy server mode'

chrome/browser/prefs/proxy_prefs.h

+// Copyright (c) 2010 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 CHROME_COMMON_PROXY_PREFS_H_
+#define CHROME_COMMON_PROXY_PREFS_H_
+#pragma once
+
+#include <string>
+
+class ProxyPrefs {
+ public:
+  // Possible types of specifying proxy settings. Do not change the order of
+  // the constants, because numeric values are exposed to users.
+  enum ProxyServerMode {
+    // Direct connection to the network, other proxy preferences are ignored.
+    DISABLED,
+
+    // Try to retrieve proxy settings from the following sources in the
+    // following order:
+    //  1. http://wpad/wpad.dat
+    //  2. The PAC script at kProxyPacUrl.
+    //  3. The settings specified in kProxyServer and kProxyBypassList
+    AUTO_DETECT,
+
+    // Same as AUTO_DETECT except that 1. is always skipped.
+    MANUAL,
+
+    // The system's proxy settings are used, other proxy preferences are
+    // ignored.
+    SYSTEM
+  };
+
+  static bool IntToMode(int in_value, ProxyServerMode* out_value);
+  static bool StringToMode(const std::string& in_value,
+                           ProxyServerMode* out_value);
+};
+
+#endif  // CHROME_COMMON_PROXY_PREFS_H_