Make extensions DSE persistent in browser prefs

chrome/browser/extensions/api/settings_overrides/settings_overrides_api.h

 // Copyright 2013 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_EXTENSIONS_API_SETTINGS_OVERRIDES_SETTINGS_OVERRIDES_API_H_
 #define CHROME_BROWSER_EXTENSIONS_API_SETTINGS_OVERRIDES_SETTINGS_OVERRIDES_API_H_
 
+#include <memory>
 #include <set>
 #include <string>
 
 #include "base/macros.h"
 #include "base/scoped_observer.h"
 #include "components/search_engines/template_url_service.h"
 #include "extensions/browser/browser_context_keyed_api_factory.h"
 #include "extensions/browser/extension_registry_observer.h"
 
 class Profile;
@@ skipping 12 matching lines @@
       GetFactoryInstance();
 
  private:
   friend class BrowserContextKeyedAPIFactory<SettingsOverridesAPI>;
 
   typedef std::set<scoped_refptr<const Extension> > PendingExtensions;
 
   // Wrappers around PreferenceAPI.
   void SetPref(const std::string& extension_id,
                const std::string& pref_key,
-               base::Value* value);
+               std::unique_ptr<base::Value> value) const;
   void UnsetPref(const std::string& extension_id,
-                 const std::string& pref_key);
+                 const std::string& pref_key) const;
 
   // ExtensionRegistryObserver implementation.
   void OnExtensionLoaded(content::BrowserContext* browser_context,
                          const Extension* extension) override;
   void OnExtensionUnloaded(content::BrowserContext* browser_context,
                            const Extension* extension,
                            UnloadedExtensionInfo::Reason reason) override;
 
   // KeyedService implementation.
   void Shutdown() override;
@@ skipping 20 matching lines @@
   DISALLOW_COPY_AND_ASSIGN(SettingsOverridesAPI);
 };
 
 template <>
 void BrowserContextKeyedAPIFactory<
     SettingsOverridesAPI>::DeclareFactoryDependencies();
 
 }  // namespace extensions
 
 #endif  // CHROME_BROWSER_EXTENSIONS_API_SETTINGS_OVERRIDES_SETTINGS_OVERRIDES_API_H_