Add ManagedUserSettingsService and a SupervisedUserPrefStore using it.

chrome/browser/managed_mode/managed_user_settings_service.h

+// Copyright 2013 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_MANAGED_MODE_MANAGED_USER_SETTINGS_SERVICE_H_
+#define CHROME_BROWSER_MANAGED_MODE_MANAGED_USER_SETTINGS_SERVICE_H_
+
+#include <string>
+#include <vector>
+
+#include "base/callback.h"
+#include "base/memory/ref_counted.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/prefs/pref_store.h"
+#include "base/values.h"
+#include "chrome/browser/managed_mode/managed_users.h"
+#include "components/browser_context_keyed_service/browser_context_keyed_service.h"
+
+class PersistentPrefStore;
+class Profile;
+
+namespace base {
+class FilePath;
+class SequencedTaskRunner;
+}
+
+// TODO(bauerb): This class is not yet fully functional.
+// This class syncs managed user settings from a server, which are mapped to
+// preferences. The downloaded settings are persisted in a PrefStore.

[Pam (message me for reviews), 2013/09/04 10:21:47]

It would be helpful to mention here too that this "storage" PrefStore isn't
connected to the PrefService.

[Bernhard Bauer, 2013/09/04 11:56:19]

Done.

+// Settings are key-value pairs, where the key uniquely identifies the setting.
+// The value is a string containing a JSON serialization of an arbitrary value,
+// which is the value of the setting.
+//
+// There are two kinds of settings handled by this class: Atomic and split
+// settings.
+// Atomic settings consist of a single key (which will be mapped to a pref key)
+// and a single (arbitrary) value.
+// Split settings encode a dictionary value and are stored as multiple Sync
+// items, one for each dictionary entry. The key for each of these Sync items
+// is the key of the split setting, followed by a separator (':') and the key
+// for the dictionary entry. The value of the Sync item is the value of the
+// dictionary entry.
+//
+// As an example, a split setting with key "Moose" and value
+//   {
+//     "foo": "bar",
+//     "baz": "blurp"
+//   }
+// would be encoded as two sync items, one with key "Moose:foo" and value "bar",
+// and one with key "Moose:baz" and value "blurp".
+class ManagedUserSettingsService : public BrowserContextKeyedService,
+                                   public PrefStore::Observer {
+ public:
+  // A callback whose first parameter is a dictionary containing all managed
+  // user settings. If the dictionary is NULL, it means that the service is
+  // inactive, i.e. the user is not managed.
+  typedef base::Callback<void(const base::DictionaryValue*)> SettingsCallback;
+
+  ManagedUserSettingsService();
+  virtual ~ManagedUserSettingsService();
+
+  // Initializes the service by loading its settings from the |pref_store|.
+  // Use this method in tests to inject a different PrefStore than the
+  // default one.
+  void Init(scoped_refptr<PersistentPrefStore> pref_store);
+
+  // Adds a callback to be called when managed user settings are initially
+  // available, or when they change.
+  void Subscribe(const SettingsCallback& callback);
+
+  // Activates the service. This happens when the user is managed.
+  void Activate();
+
+  // Whether managed user settings are available.
+  bool IsReady();
+
+  // Clears all managed user settings and items.
+  void Clear();
+
+  // Sets the setting with the given |key| to a copy of the given |value|.
+  void SetLocalSettingForTesting(const std::string& key,
+                                 scoped_ptr<base::Value> value);
+
+  // BrowserContextKeyedService implementation:
+  virtual void Shutdown() OVERRIDE;
+
+  // PrefStore::Observer implementation:
+  virtual void OnPrefValueChanged(const std::string& key) OVERRIDE;
+  virtual void OnInitializationCompleted(bool success) OVERRIDE;
+
+ private:
+  base::DictionaryValue* GetOrCreateDictionary(const std::string& key) const;
+  base::DictionaryValue* GetAtomicSettings() const;
+  base::DictionaryValue* GetSplitSettings() const;
+  base::DictionaryValue* GetQueuedItems() const;
+
+  // Returns a dictionary with all managed user settings if the service is
+  // active, or NULL otherwise.
+  scoped_ptr<base::DictionaryValue> GetSettings();
+
+  // Sends the settings to all subscribers. This method should be called by the
+  // subclass whenever the settings change.
+  void InformSubscribers();
+
+  // Used for persisting the settings. Unlike other PrefStores, this one is not
+  // directly hooked up to the PrefService.
+  scoped_refptr<PersistentPrefStore> store_;
+
+  bool active_;
+
+  // A set of local settings that are fixed and not configured remotely.
+  scoped_ptr<base::DictionaryValue> local_settings_;
+
+  std::vector<SettingsCallback> subscribers_;
+
+  DISALLOW_COPY_AND_ASSIGN(ManagedUserSettingsService);
+};
+
+#endif  // CHROME_BROWSER_MANAGED_MODE_MANAGED_USER_SETTINGS_SERVICE_H_