Disable proxy config button and show banner if proxy prefs are managed.

chrome/browser/pref_set_observer.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_BROWSER_PREF_SET_OBSERVER_H_
+#define CHROME_BROWSER_PREF_SET_OBSERVER_H_
+
+#include <set>
+
+#include "base/basictypes.h"
+#include "chrome/browser/pref_service.h"
+#include "chrome/common/notification_observer.h"
+
+// Observes the state of a set of preferences and allows to query their combined
+// managed bits.
+class PrefSetObserver : public NotificationObserver {
+ public:
+  // Initialize with an empty set of preferences.
+  PrefSetObserver(PrefService* pref_service,
+                  NotificationObserver* observer);
+  virtual ~PrefSetObserver();
+
+  // Add a |pref| to the set of preferences to observe.
+  void AddPref(const std::wstring& pref);
+  // Remove |pref| from the set of observed peferences.
+  void RemovePref(const std::wstring& pref);
+
+  // Check whether |pref| is in the set of observed preferences.
+  bool IsObserved(const std::wstring& pref);
+  // Check whether any of the observed preferences has the managed bit set.
+  bool IsManaged();
+
+  // Create a pref set observer for all preferences relavant to proxies.
+  static PrefSetObserver* CreateProxyPrefSetObserver(
+      PrefService* pref_service,
+      NotificationObserver* observer);
+
+ private:
+  // Overridden from NotificationObserver.
+  virtual void Observe(NotificationType type,
+                       const NotificationSource& source,
+                       const NotificationDetails& details);
+
+  typedef std::set<std::wstring> PrefSet;
+  PrefSet prefs_;
+
+  PrefService* pref_service_;
+  NotificationObserver* observer_;
+
+  DISALLOW_COPY_AND_ASSIGN(PrefSetObserver);
+};
+
+#endif  // CHROME_BROWSER_PREF_SET_OBSERVER_H_