Introduce a separate preference for 'proxy server mode'

chrome/browser/prefs/proxy_prefs.h

Index: chrome/browser/prefs/proxy_prefs.h
diff --git a/chrome/browser/prefs/proxy_prefs.h b/chrome/browser/prefs/proxy_prefs.h
new file mode 100644
index 0000000000000000000000000000000000000000..bbeb44d79901bda686a58bb71391859a97152c2f
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+++ b/chrome/browser/prefs/proxy_prefs.h
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+// 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_BROWSER_PREFS_PROXY_PREFS_H_
+#define CHROME_BROWSER_PREFS_PROXY_PREFS_H_
+#pragma once
+
+#include <string>
+
+namespace ProxyPrefs {
+
+// Possible types of specifying proxy settings. Do not change the order of
+// the constants, because numeric values are exposed to users.
+// If you add an enum constant, you should also add a string to
+// kProxyModeNames in the .cc file.
+enum ProxyMode {
+  // Direct connection to the network, other proxy preferences are ignored.
+  MODE_DIRECT = 0,
+
+  // Try to retrieve a PAC script from http://wpad/wpad.dat or fall back to
+  // direct connection.
+  MODE_AUTO_DETECT = 1,
+
+  // Try to retrieve a PAC script from kProxyPacURL or fall back to direct
+  // connection.
+  MODE_PAC_SCRIPT = 2,
+
+  // Use the settings specified in kProxyServer and kProxyBypassList.
+  MODE_FIXED_SERVERS = 3,
+
+  // The system's proxy settings are used, other proxy preferences are
+  // ignored.
+  MODE_SYSTEM = 4,
+
+  kModeCount
+};
+
+bool IntToProxyMode(int in_value, ProxyMode* out_value);
+bool StringToProxyMode(const std::string& in_value,
+                       ProxyMode* out_value);
+
+}  // namespace ProxyPrefs
+
+#endif  // CHROME_BROWSER_PREFS_PROXY_PREFS_H_