Make CrOS proxy configuration write prefs directly.

net/proxy/proxy_bypass_rules.h

Index: net/proxy/proxy_bypass_rules.h
diff --git a/net/proxy/proxy_bypass_rules.h b/net/proxy/proxy_bypass_rules.h
index ad8afdc213006156c1badb699cef84ab55f20dde..c0f5df33d2044eae2398c828c6a910831bf52714 100644
--- a/net/proxy/proxy_bypass_rules.h
+++ b/net/proxy/proxy_bypass_rules.h
@@ -1,4 +1,4 @@
-// Copyright (c) 2010 The Chromium Authors. All rights reserved.
+// Copyright (c) 2011 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.
 
@@ -153,6 +153,10 @@ class ProxyBypassRules {
   // NOTE: Use AddRuleFromString() unless you truly need this behavior.
   bool AddRuleFromStringUsingSuffixMatching(const std::string& raw);
 
+  // Converts the rules to string representation. Inverse operation to
+  // ParseFromString().
+  std::string ToString() const;
+
   // Removes all the rules.
   void Clear();