Add a HostContentSettingsMap layer for Supervised Users.

chrome/browser/content_settings/content_settings_supervised_provider.h

+// Copyright (c) 2015 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_SUPERVISED_PROVIDER_H_
+#define CHROME_BROWSER_CONTENT_SETTINGS_CONTENT_SETTINGS_SUPERVISED_PROVIDER_H_
+
+// A content setting provider that is set by the custodian of a supervised user.
+
+#include "components/content_settings/core/browser/content_settings_binary_value_map.h"
+#include "components/content_settings/core/browser/content_settings_observable_provider.h"
+
+class PrefService;
+
+namespace base {
+class Lock;

[Bernhard Bauer, 2015/02/26 18:03:54]

This class has a base::Lock member, so the fact that this compiles tells me that
we are already including the header transitively, which makes this forward
declaration unnecessary.

The include-what-you-use thing to do is to include base/synchronization/lock.h
instead.

[knn, 2015/02/27 10:43:53]

Done.

[Bernhard Bauer, 2015/02/27 11:20:25]

Include the header file here pls? (You can then remove it from the .cc file, I
guess.)

[knn, 2015/02/27 12:05:14]

Done.

+}
+
+namespace content_settings {
+
+// SupervisedProvider that provides content-settings managed by the custodian
+// of a supervised user.
+class SupervisedProvider : public ObservableProvider {
+ public:
+  // ProviderInterface implementations.
+  RuleIterator* GetRuleIterator(ContentSettingsType content_type,
+                                const ResourceIdentifier& resource_identifier,
+                                bool incognito) const override;
+
+  bool SetWebsiteSetting(const ContentSettingsPattern& primary_pattern,
+                         const ContentSettingsPattern& secondary_pattern,
+                         ContentSettingsType content_type,
+                         const ResourceIdentifier& resource_identifier,
+                         base::Value* value) override;
+
+  void ClearAllContentSettingsRules(ContentSettingsType content_type) override;
+
+  void ShutdownOnUIThread() override;
+
+  // Callback on receiving settings from the supervised user settings service.
+  void OnSupervisedSettingsAvailable(const base::DictionaryValue* settings);
+
+ private:
+  BinaryValueMap value_map_;
+
+  // Used around accesses to the |value_map_| object to guarantee
+  // thread safety.
+  mutable base::Lock lock_;
+};
+
+}  // namespace content_settings
+
+#endif  // CHROME_BROWSER_CONTENT_SETTINGS_CONTENT_SETTINGS_SUPERVISED_PROVIDER_H_