sync: Implementation of Priority Preferences.

components/user_prefs/pref_registry_syncable.h

 // 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 COMPONENTS_USER_PREFS_PREF_REGISTRY_SYNCABLE_H_
 #define COMPONENTS_USER_PREFS_PREF_REGISTRY_SYNCABLE_H_
 
 #include <set>
 #include <string>
 
@@ skipping 12 matching lines @@
 //
 // Classes or components that want to register such preferences should
 // define a static function named RegisterUserPrefs that takes a
 // PrefRegistrySyncable*, and the top-level application using the
 // class or embedding the component should call this function at an
 // appropriate time before the PrefService for these preferences is
 // constructed. See e.g. chrome/browser/prefs/browser_prefs.cc which
 // does this for Chrome.
 class USER_PREFS_EXPORT PrefRegistrySyncable : public PrefRegistry {
  public:
-  typedef base::Callback<void(const char* path)> SyncableRegistrationCallback;
-
   // Enum used when registering preferences to determine if it should
-  // be synced or not.
+  // be synced or not. Syncable priority preferences are preferences that are
+  // never encrypted and are synced before other datatypes. Because they're
+  // never encrypted, on first sync, they can be synced down before the user
+  // is prompted for a passphrase.
   enum PrefSyncStatus {
     UNSYNCABLE_PREF,
-    SYNCABLE_PREF
+    SYNCABLE_PREF,
+    SYNCABLE_PRIORITY_PREF,
   };
 
+  typedef
+      base::Callback<void(const char* path, const PrefSyncStatus sync_status)>
+          SyncableRegistrationCallback;
+
   PrefRegistrySyncable();
 
+  typedef std::map<std::string, PrefSyncStatus> PrefToStatus;
+
   // Retrieve the set of syncable preferences currently registered.
-  const std::set<std::string>& syncable_preferences() const;
+  const PrefToStatus& syncable_preferences() const;
 
   // Exactly one callback can be set for the event of a syncable
   // preference being registered. It will be fired after the
   // registration has occurred.
   //
   // Calling this method after a callback has already been set will
   // make the object forget the previous callback and use the new one
   // instead.
   void SetSyncableRegistrationCallback(const SyncableRegistrationCallback& cb);
 
@@ skipping 48 matching lines @@
  private:
   virtual ~PrefRegistrySyncable();
 
   void RegisterSyncablePreference(const char* path,
                                   base::Value* default_value,
                                   PrefSyncStatus sync_status);
 
   SyncableRegistrationCallback callback_;
 
   // Contains the names of all registered preferences that are syncable.
-  std::set<std::string> syncable_preferences_;
+  PrefToStatus syncable_preferences_;
 
   DISALLOW_COPY_AND_ASSIGN(PrefRegistrySyncable);
 };
 
 #endif  // COMPONENTS_USER_PREFS_PREF_REGISTRY_SYNCABLE_H_