Pref service: Add a ScopedDictionaryPrefUpdate to track value changes.

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 <map>
 #include <memory>
+#include <set>
 #include <string>
+#include <unordered_map>
+#include <utility>
 #include <vector>
 
 #include "base/macros.h"
 #include "components/prefs/persistent_pref_store.h"
 #include "components/prefs/pref_value_store.h"
 #include "services/preferences/public/cpp/pref_store_client_mixin.h"
 #include "services/preferences/public/interfaces/preferences.mojom.h"
 
 namespace base {
 class Value;
@@ skipping 16 matching lines @@
   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;
   void ReportValueChanged(const std::string& key, uint32_t flags) override;
+  void ReportSubValuesChanged(
+      const std::string& key,
+      std::set<std::vector<std::string>> path_components,
+      uint32_t flags) override;
   void SetValueSilently(const std::string& key,
                         std::unique_ptr<base::Value> value,
                         uint32_t flags) override;
 
   // PersistentPrefStore:
   bool ReadOnly() const override;
   PrefReadError GetReadError() const override;
   PrefReadError ReadPrefs() override;
   void ReadPrefsAsync(ReadErrorDelegate* error_delegate) override;
   void CommitPendingWrite() override;
   void SchedulePendingLossyWrites() override;
   void ClearMutableValues() override;
 
  protected:
   // base::RefCounted<PrefStore>:
   ~PersistentPrefStoreClient() override;
 
  private:
   void OnConnect(mojom::PersistentPrefStoreConnectionPtr connection,
                  std::unordered_map<PrefValueStore::PrefStoreType,
                                     prefs::mojom::PrefStoreConnectionPtr>
                      other_pref_stores);
 
-  void QueueWrite(const std::string& key, uint32_t flags);
+  void QueueWrite(const std::string& key,
+                  std::set<std::vector<std::string>> path_components,
+                  uint32_t flags);
   void FlushPendingWrites();
 
   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::map<std::string, uint32_t> pending_writes_;
+  std::map<std::string, std::pair<std::set<std::vector<std::string>>, uint32_t>>
+      pending_writes_;
 
   std::unique_ptr<ReadErrorDelegate> error_delegate_;
   std::vector<PrefValueStore::PrefStoreType> already_connected_types_;
 
   base::WeakPtrFactory<PersistentPrefStoreClient> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(PersistentPrefStoreClient);
 };
 
 }  // namespace prefs
 
 #endif  // SERVICES_PREFERENCES_PUBLIC_CPP_PERSISTENT_PREF_STORE_CLIENT_H_