Remove PrefServiceSimple, replacing it with PrefService and PrefRegistrySimple.

chrome/browser/prefs/pref_registry.h

Index: chrome/browser/prefs/pref_registry.h
diff --git a/chrome/browser/prefs/pref_registry.h b/chrome/browser/prefs/pref_registry.h
new file mode 100644
index 0000000000000000000000000000000000000000..d13e72a993a004c3c13d9cfae5a703fd2ca59e42
--- /dev/null
+++ b/chrome/browser/prefs/pref_registry.h
@@ -0,0 +1,63 @@
+// Copyright (c) 2012 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_PREF_REGISTRY_H_
+#define CHROME_BROWSER_PREFS_PREF_REGISTRY_H_
+
+#include "base/memory/ref_counted.h"
+#include "base/memory/ref_counted.h"

[Mattias Nissler (ping if slow), 2013/01/25 14:57:11]

once is enough ;)

[Jói, 2013/01/29 16:10:02]

Done.

+#include "base/prefs/default_pref_store.h"
+
+namespace base {
+class Value;
+}
+
+class PrefService;
+
+// Preferences need to be registered with a type and default value
+// before they are used.
+//
+// The way you use a PrefRegistry is that you register all required
+// preferences on it, then pass it as a construction parameter to
+// PrefService.
+//
+// Currently, registrations after constructing the PrefService will
+// also work, but this is being deprecated.
+class PrefRegistry {
+ public:
+  PrefRegistry();
+
+  // Only valid after this object has been used to construct a PrefService.
+  virtual void DeprecatedUnregisterPreference(const char* path);
+
+ protected:
+  // Interface used by PrefService to retrieve registered default values. This
+  // is a transfer of ownership; this object loses its reference to the
+  // default values when this method is called.
+  void RetrieveDefaults(scoped_refptr<DefaultPrefStore>* result);

[Mattias Nissler (ping if slow), 2013/01/25 14:57:11]

I'd make this public with the eventual goal of removing the friend class
PrefService declaration.

Also, why isn't this just a public accessor like so:

scoped_refptr<PrefStore> pref_store() { return default_prefs_; }

[Jói, 2013/01/29 16:10:02]

Done.

+
+  // Used by subclasses to register a default value for a preference.
+  void RegisterPreference(const char* path, base::Value* default_value);
+
+ private:
+  // This friend and member are needed for registrations after
+  // construction time, and for DeprecatedUnregisterPreference.
+  // PrefService sets the pref_service_ member once it receives this
+  // object at construction time.
+  friend class PrefService;
+  PrefService* pref_service_;
+
+  // Friend so that PrefRegistry can be used in place of a PrefStore
+  // for its default_store construction parameter.
+  friend class PrefValueStore;

[Mattias Nissler (ping if slow), 2013/01/25 14:57:11]

I don't understand this comment, why can a PrefRegistry be used in place of a
PrefStore? Why would PrefValueStore be concerned with either PrefStore or
PrefRegistry?

[Jói, 2013/01/29 16:10:02]

This bit of ugliness is gone.

+
+  // TODO(joi): Temporary until we have a PrefRegistrySyncable.
+  friend class PrefServiceSyncable;
+
+  scoped_refptr<DefaultPrefStore> default_prefs_;
+
+  DISALLOW_COPY_AND_ASSIGN(PrefRegistry);
+};
+
+#endif  // CHROME_BROWSER_PREFS_PREF_REGISTRY_H_