Convert //ios from scoped_ptr to std::unique_ptr.

ios/chrome/browser/undo/bookmark_undo_service_factory.cc

Index: ios/chrome/browser/undo/bookmark_undo_service_factory.cc
diff --git a/ios/chrome/browser/undo/bookmark_undo_service_factory.cc b/ios/chrome/browser/undo/bookmark_undo_service_factory.cc
index f08731dc4b6577ca87bc9616beb7e6c2a2ad056e..b500a4aed9ef3e24abf355836ee39c4665d7d7b6 100644
--- a/ios/chrome/browser/undo/bookmark_undo_service_factory.cc
+++ b/ios/chrome/browser/undo/bookmark_undo_service_factory.cc
@@ -4,6 +4,7 @@
 
 #include "ios/chrome/browser/undo/bookmark_undo_service_factory.h"
 
+#include "base/memory/ptr_util.h"
 #include "base/memory/singleton.h"
 #include "components/keyed_service/ios/browser_state_dependency_manager.h"
 #include "components/undo/bookmark_undo_service.h"
@@ -39,9 +40,10 @@ BookmarkUndoServiceFactory::BookmarkUndoServiceFactory()
 BookmarkUndoServiceFactory::~BookmarkUndoServiceFactory() {
 }
 
-scoped_ptr<KeyedService> BookmarkUndoServiceFactory::BuildServiceInstanceFor(
+std::unique_ptr<KeyedService>
+BookmarkUndoServiceFactory::BuildServiceInstanceFor(
     web::BrowserState* context) const {
-  return make_scoped_ptr(new BookmarkUndoService);
+  return base::WrapUnique(new BookmarkUndoService);
 }
 
 }  // namespace ios