Switch Preferences to use Factory

chrome/browser/prefs/preferences_manager.h

Index: chrome/browser/prefs/preferences_manager.h
diff --git a/chrome/browser/prefs/preferences_manager.h b/chrome/browser/prefs/preferences_manager.h
index 9ffc67aa4c2e4c51a18437d5ee72430977f5ba59..8f2272a0f8f03bb48f35b1ac3450294b16446d8b 100644
--- a/chrome/browser/prefs/preferences_manager.h
+++ b/chrome/browser/prefs/preferences_manager.h
@@ -25,7 +25,8 @@ class Profile;
 // the requested preferences, notifying the client of all changes.
 class PreferencesManager : public prefs::mojom::PreferencesManager {
  public:
-  explicit PreferencesManager(Profile* profile);
+  PreferencesManager(prefs::mojom::PreferencesObserverPtr client,
+                     Profile* profile);
   ~PreferencesManager() override;
 
  private:
@@ -35,7 +36,6 @@ class PreferencesManager : public prefs::mojom::PreferencesManager {
   void PreferenceChanged(const std::string& preference_name);
 
   // mojom::PreferencesManager:
-  void AddObserver(prefs::mojom::PreferencesObserverPtr client) override;
   void SetPreferences(
       std::unique_ptr<base::DictionaryValue> preferences) override;
   void Subscribe(const std::vector<std::string>& preferences) override;