Implement preference and policy based content settings providers.

chrome/browser/content_settings/policy_content_settings_provider.h

Index: chrome/browser/content_settings/policy_content_settings_provider.h
diff --git a/chrome/browser/content_settings/policy_content_settings_provider.h b/chrome/browser/content_settings/policy_content_settings_provider.h
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+// 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_POLICY_CONTENT_SETTINGS_PROVIDER_H_
+#define CHROME_BROWSER_CONTENT_SETTINGS_POLICY_CONTENT_SETTINGS_PROVIDER_H_
+#pragma once
+
+// A content settings provider that takes its settings out of policies.
+
+#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 PolicyContentSettingsProvider : public ContentSettingsProviderInterface,
+                                      public NotificationObserver {
+ public:
+  PolicyContentSettingsProvider(Profile* profile);
+  virtual ~PolicyContentSettingsProvider();
+
+  // 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 retrieved from |prefs|.
+  void ReadDefaultSettingsFromPrefs(const PrefService* prefs,
+                                    ContentSettings* settings);
+
+  // Reads the policy controlled default settings for a specific content type.
+  void UpdateManagedDefaultSetting(const PrefService* prefs,
+                                   ContentSettingsType content_type,
+                                   ContentSettings* settings);
+
+
+  // Copies of the pref data, so that we can read it on the IO thread.
+  ContentSettings managed_default_content_settings_;
+
+  Profile* profile_;
+
+  // Whether this settings map is for an OTR session.
+  bool is_off_the_record_;
+
+  // Used around accesses to the managed_default_content_settings_ object to
+  // guarantee thread safety.
+  mutable Lock lock_;
+
+  PrefChangeRegistrar pref_change_registrar_;
+  NotificationRegistrar notification_registrar_;
+
+  DISALLOW_COPY_AND_ASSIGN(PolicyContentSettingsProvider);
+};
+
+#endif  // CHROME_BROWSER_CONTENT_SETTINGS_POLICY_CONTENT_SETTINGS_PROVIDER_H_