Use rvalue reference instead of ExtensionBuilder::pass()

C++ 11 enables rvalue reference with std::move() so that removing legacy ListBuilder::Pass().

BUG=563649
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Review URL: https://codereview.chromium.org/1511103003

Cr-Commit-Position: refs/heads/master@{#365969}
diff --git a/extensions/common/test_util.cc b/extensions/common/test_util.cc
index 9a9312a..eb857fd 100644
--- a/extensions/common/test_util.cc
+++ b/extensions/common/test_util.cc
@@ -13,16 +13,16 @@
 namespace extensions {
 namespace test_util {
 
-ExtensionBuilder& BuildExtension(ExtensionBuilder& builder) {
-  return builder
-         .SetManifest(DictionaryBuilder()
-                      .Set("name", "Test extension")
-                      .Set("version", "1.0")
-                      .Set("manifest_version", 2));
+ExtensionBuilder BuildExtension(ExtensionBuilder builder) {
+  builder.SetManifest(DictionaryBuilder()
+                          .Set("name", "Test extension")
+                          .Set("version", "1.0")
+                          .Set("manifest_version", 2));
+  return builder;
 }
 
-ExtensionBuilder& BuildApp(ExtensionBuilder& builder) {
-  return builder.SetManifest(
+ExtensionBuilder BuildApp(ExtensionBuilder builder) {
+  builder.SetManifest(
       DictionaryBuilder()
           .Set("name", "Test extension")
           .Set("version", "1.0")
@@ -33,6 +33,7 @@
                    extensions::DictionaryBuilder().Set(
                        "scripts", std::move(extensions::ListBuilder().Append(
                                       "background.js"))))));
+  return builder;
 }
 
 scoped_refptr<Extension> CreateEmptyExtension() {