Policy: plugins disabled by policy should honor policy changes without Chrome relaunch.

BUG=54620
TEST=PrefChangeRegistrarTest.*

Review URL: http://codereview.chromium.org/3316007

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@59094 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 50 insertions, 0 deletions

diff --git a/chrome/browser/prefs/pref_change_registrar.h b/chrome/browser/prefs/pref_change_registrar.h
new file mode 100644
index 0000000..cd8f5eb
--- /dev/null
+++ b/chrome/browser/prefs/pref_change_registrar.h
@@ -0,0 +1,50 @@
+// 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_PREF_CHANGE_REGISTRAR_H_
+#define CHROME_BROWSER_PREFS_PREF_CHANGE_REGISTRAR_H_
+#pragma once
+
+#include <set>
+#include <string>
+
+#include "base/basictypes.h"
+
+class PrefService;
+class NotificationObserver;
+
+// Automatically manages the registration of one or more pref change observers
+// with a PrefStore. Functions much like NotificationRegistrar, but specifically
+// manages observers of preference changes. When the Registrar is destroyed,
+// all registered observers are automatically unregistered with the PrefStore.
+class PrefChangeRegistrar {
+ public:
+  PrefChangeRegistrar();
+  virtual ~PrefChangeRegistrar();
+
+  // Must be called before adding or removing observers.
+  void Init(PrefService* service);
+
+  // Adds an pref observer for the specified pref |path| and |obs| observer
+  // object. All registered observers will be automatically unregistered
+  // when the registrar's destructor is called unless the observer has been
+  // explicitly removed by a call to Remove beforehand.
+  void Add(const char* path,
+           NotificationObserver* obs);
+
+  // Removes a preference observer that has previously been added with a call to
+  // Add.
+  void Remove(const char* path,
+              NotificationObserver* obs);
+
+ private:
+  typedef std::pair<std::string, NotificationObserver*> ObserverRegistration;
+
+  std::set<ObserverRegistration> observers_;
+  PrefService* service_;
+
+  DISALLOW_COPY_AND_ASSIGN(PrefChangeRegistrar);
+};
+
+#endif  // CHROME_BROWSER_PREFS_PREF_CHANGE_REGISTRAR_H_