Implement preference and policy based content settings providers.

chrome/browser/content_settings/pref_content_settings_provider.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_CONTENT_SETTINGS_PREF_CONTENT_SETTINGS_PROVIDER_H_
+#define CHROME_BROWSER_CONTENT_SETTINGS_PREF_CONTENT_SETTINGS_PROVIDER_H_
+#pragma once
+
+// A content settings provider that takes its settings out of the pref service.
+
+#include "base/basictypes.h"
+#include "base/lock.h"
+#include "chrome/browser/content_settings/content_settings_provider.h"
+#include "chrome/browser/prefs/pref_change_registrar.h"
+#include "chrome/common/notification_observer.h"
+#include "chrome/common/notification_registrar.h"
+
+class ContentSettingsDetails;
+class DictionaryValue;
+class PrefService;
+class Profile;
+
+class PrefContentSettingsProvider : public ContentSettingsProviderInterface,
+                                    public NotificationObserver {
+ public:
+  explicit PrefContentSettingsProvider(Profile* profile);
+  virtual ~PrefContentSettingsProvider();
+
+  // ContentSettingsProviderInterface implementation.
+  virtual bool CanProvideDefaultSetting(ContentSettingsType content_type) const;
+  virtual ContentSetting ProvideDefaultSetting(
+      ContentSettingsType content_type) const;
+  virtual void UpdateDefaultSetting(ContentSettingsType content_type,
+                                    ContentSetting setting);
+  virtual void ResetToDefaults();
+  virtual bool DefaultSettingIsManaged(ContentSettingsType content_type) const;
+
+  static void RegisterUserPrefs(PrefService* prefs);
+
+  // NotificationObserver implementation.
+  virtual void Observe(NotificationType type,
+                       const NotificationSource& source,
+                       const NotificationDetails& details);
+
+ private:
+  // Informs observers that content settings have changed. Make sure that
+  // |lock_| is not held when calling this, as listeners will usually call one
+  // of the GetSettings functions in response, which would then lead to a
+  // mutex deadlock.
+  void NotifyObservers(const ContentSettingsDetails& details);
+
+  void UnregisterObservers();
+
+  // Sets the fields of |settings| based on the values in |dictionary|.
+  void GetSettingsFromDictionary(const DictionaryValue* dictionary,
+                                 ContentSettings* settings);
+
+  // Forces the default settings to be explicitly set instead of themselves
+  // being CONTENT_SETTING_DEFAULT.
+  void ForceDefaultsToBeExplicit();
+
+  // Reads the default settings from the preferences service. If |overwrite| is
+  // true and the preference is missing, the local copy will be cleared as well.
+  void ReadDefaultSettings(bool overwrite);
+
+  // Copies of the pref data, so that we can read it on the IO thread.
+  ContentSettings default_content_settings_;
+
+  Profile* profile_;
+
+  // Whether this settings map is for an OTR session.
+  bool is_off_the_record_;
+
+  // Used around accesses to the default_content_settings_ object to guarantee
+  // thread safety.
+  mutable Lock lock_;
+
+  PrefChangeRegistrar pref_change_registrar_;
+  NotificationRegistrar notification_registrar_;
+
+  // Whether we are currently updating preferences, this is used to ignore
+  // notifications from the preferences service that we triggered ourself.
+  bool updating_preferences_;
+
+  DISALLOW_COPY_AND_ASSIGN(PrefContentSettingsProvider);
+};
+
+#endif  // CHROME_BROWSER_CONTENT_SETTINGS_PREF_CONTENT_SETTINGS_PROVIDER_H_