Use rvalue reference instead of ExtensionBuilder::pass()

extensions/common/test_util.h

 // Copyright 2014 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 EXTENSIONS_COMMON_TEST_UTIL_H_
 #define EXTENSIONS_COMMON_TEST_UTIL_H_
 
 #include <string>
 
 #include "base/memory/ref_counted.h"
 
 namespace extensions {
 class Extension;
 class ExtensionBuilder;
 
 namespace test_util {
 
 // Adds an extension manifest to a builder.
-ExtensionBuilder& BuildExtension(ExtensionBuilder& builder);
+ExtensionBuilder BuildExtension(ExtensionBuilder builder);
 
 // Adds an app manifest to a builder.
-ExtensionBuilder& BuildApp(ExtensionBuilder& builder);
+ExtensionBuilder BuildApp(ExtensionBuilder builder);
 
 // Creates an extension instance that can be attached to an ExtensionFunction
 // before running it.
 scoped_refptr<Extension> CreateEmptyExtension();
 
 // Create an extension with a variable |id|, for tests that require multiple
 // extensions side-by-side having distinct IDs.
 scoped_refptr<Extension> CreateEmptyExtension(const std::string& id);
 
 }  // namespace test_util
 }  // namespace extensions
 
 #endif  // EXTENSIONS_COMMON_TEST_UTIL_H_