Pref service: Add initial support for pref registration.

services/preferences/public/cpp/persistent_pref_store_client.h

 // Copyright 2017 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 SERVICES_PREFERENCES_PUBLIC_CPP_PERSISTENT_PREF_STORE_CLIENT_H_
 #define SERVICES_PREFERENCES_PUBLIC_CPP_PERSISTENT_PREF_STORE_CLIENT_H_
 
 #include <memory>
 #include <string>
 
 #include "base/macros.h"
 #include "components/prefs/persistent_pref_store.h"
 #include "services/preferences/public/cpp/pref_store_client_mixin.h"
 #include "services/preferences/public/interfaces/preferences.mojom.h"
 
 namespace base {
 class Value;
 }
 
+class PrefRegistry;
+
 namespace prefs {
 
 // An implementation of PersistentPrefStore backed by a
 // mojom::PersistentPrefStore and a mojom::PrefStoreObserver.
 class PersistentPrefStoreClient
     : public PrefStoreClientMixin<PersistentPrefStore> {
  public:
-  explicit PersistentPrefStoreClient(mojom::PrefStoreConnectorPtr connector);
+  PersistentPrefStoreClient(mojom::PrefStoreConnectorPtr connector,
+                            scoped_refptr<PrefRegistry> pref_registry);
 
   explicit PersistentPrefStoreClient(
       mojom::PersistentPrefStoreConnectionPtr connection);
 
   // WriteablePrefStore:
   void SetValue(const std::string& key,
                 std::unique_ptr<base::Value> value,
                 uint32_t flags) override;
   void RemoveValue(const std::string& key, uint32_t flags) override;
   bool GetMutableValue(const std::string& key, base::Value** result) override;
@@ skipping 15 matching lines @@
   // base::RefCounted<PrefStore>:
   ~PersistentPrefStoreClient() override;
 
  private:
   void OnConnect(mojom::PersistentPrefStoreConnectionPtr connection,
                  std::unordered_map<PrefValueStore::PrefStoreType,
                                     prefs::mojom::PrefStoreConnectionPtr>
                      other_pref_stores);
 
   mojom::PrefStoreConnectorPtr connector_;
+  scoped_refptr<PrefRegistry> pref_registry_;
   bool read_only_ = false;
   PrefReadError read_error_ = PersistentPrefStore::PREF_READ_ERROR_NONE;
   mojom::PersistentPrefStorePtr pref_store_;
 
   std::unique_ptr<ReadErrorDelegate> error_delegate_;
 
   DISALLOW_COPY_AND_ASSIGN(PersistentPrefStoreClient);
 };
 
 }  // namespace prefs
 
 #endif  // SERVICES_PREFERENCES_PUBLIC_CPP_PERSISTENT_PREF_STORE_CLIENT_H_