Add a global on/off switch for content settings and expose a toggle on the Website Settings options…

chrome/browser/content_settings/content_settings_override_provider.h

+// Copyright 2014 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_CONTENT_SETTINGS_CONTENT_SETTINGS_OVERRIDE_PROVIDER_H_
+#define CHROME_BROWSER_CONTENT_SETTINGS_CONTENT_SETTINGS_OVERRIDE_PROVIDER_H_
+
+#include <map>
+
+#include "base/macros.h"
+#include "base/synchronization/lock.h"
+#include "components/content_settings/core/common/content_settings_types.h"
+
+class PrefService;
+
+namespace user_prefs {
+class PrefRegistrySyncable;
+}
+
+namespace content_settings {
+
+// OverrideProvider contains if certain content settings are enabled or
+// globally disabled.
+class OverrideProvider {
+ public:
+  static void RegisterProfilePrefs(user_prefs::PrefRegistrySyncable* registry);
+
+  OverrideProvider(PrefService* prefs, bool incognito);
+  virtual ~OverrideProvider();
+
+  // Returns if |content_type| is enabled. If it is not enabled, the content
+  // setting type is considered globally disabled and acts as though it is
+  // blocked. If it is enabled, the content setting type's permission is granted
+  // by the other providers.
+  bool IsEnabled(ContentSettingsType content_type) const;
+
+  // Sets |content_type|'s enabled status.
+  void SetContentSetting(ContentSettingsType content_type, bool is_enabled);
+
+ private:
+  // Reads the override settings from the preferences service.
+  void ReadOverrideSettings();
+
+  // Copies of the pref data, so that we can read it on the IO thread.
+  std::map<ContentSettingsType, bool> override_settings_;
+
+  PrefService* prefs_;
+
+  bool is_incognito_;
+
+  // Used around accesses to the |override_content_settings_| object to
+  // guarantee thread safety.
+  mutable base::Lock lock_;
+
+  DISALLOW_COPY_AND_ASSIGN(OverrideProvider);
+};
+
+}  // namespace content_settings
+
+#endif  // CHROME_BROWSER_CONTENT_SETTINGS_CONTENT_SETTINGS_OVERRIDE_PROVIDER_H_