Add ManagedUserSettingsService and a SupervisedUserPrefStore using it.

chrome/browser/prefs/supervised_user_pref_store.h

Index: chrome/browser/prefs/supervised_user_pref_store.h
diff --git a/chrome/browser/prefs/supervised_user_pref_store.h b/chrome/browser/prefs/supervised_user_pref_store.h
new file mode 100644
index 0000000000000000000000000000000000000000..6584dcffb3a689e3efc01ababa5f66f70e749668
--- /dev/null
+++ b/chrome/browser/prefs/supervised_user_pref_store.h
@@ -0,0 +1,52 @@
+// 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_PREFS_SUPERVISED_USER_PREF_STORE_H_
+#define CHROME_BROWSER_PREFS_SUPERVISED_USER_PREF_STORE_H_
+
+#include "base/memory/scoped_ptr.h"
+#include "base/observer_list.h"
+#include "base/prefs/pref_store.h"
+#include "chrome/browser/managed_mode/managed_users.h"
+
+namespace base {
+class DictionaryValue;
+class Value;
+}
+
+class ManagedUserSettingsService;
+class PrefValueMap;
+
+// A PrefStore that gets its values from managed user settings via the
+// ManagedUserSettingsService passed in at construction.

[Pam (message me for reviews), 2013/08/30 13:35:53]

And that gets -- will get -- its settings from the ManagedModePolicyProvider?
This seems rather more complicated, more layers, than necessary. Although maybe
I just need a clear picture of how it interrelates to see why it's all needed.

[Bernhard Bauer, 2013/08/30 14:54:27]

No, ManagedModePolicyProvider will go away in favor of
ManagedUserSettingsSyncService (I know, awesome name).
The final CL is at https://codereview.chromium.org/23376002/. We add one
additional layer on the way from Sync to preferences, because we separate the
SyncableService from the class that maps settings to preferences.

+class SupervisedUserPrefStore : public PrefStore {
+ public:
+  SupervisedUserPrefStore(
+      ManagedUserSettingsService* managed_user_settings_service);
+
+  // PrefStore overrides:
+  virtual bool GetValue(const std::string& key,
+                        const base::Value** value) const OVERRIDE;
+  virtual void AddObserver(PrefStore::Observer* observer) OVERRIDE;
+  virtual void RemoveObserver(PrefStore::Observer* observer) OVERRIDE;
+  virtual bool HasObservers() const OVERRIDE;
+  virtual bool IsInitializationComplete() const OVERRIDE;
+
+ private:
+  virtual ~SupervisedUserPrefStore();
+
+  void CopySettingsValue(const base::DictionaryValue* settings,

[Pam (message me for reviews), 2013/08/30 13:35:53]

Comment please

[Bernhard Bauer, 2013/08/30 14:54:27]

Done.

+                         const char* settings_name,
+                         const char* pref_name);
+
+  void OnNewSettingsAvailable(const base::DictionaryValue* settings);
+
+  base::WeakPtrFactory<SupervisedUserPrefStore> weak_ptr_factory_;
+
+  scoped_ptr<PrefValueMap> prefs_;
+
+  ObserverList<PrefStore::Observer, true> observers_;
+};
+
+#endif  // CHROME_BROWSER_PREFS_SUPERVISED_USER_PREF_STORE_H_