Convert JsonWriter::Write to taking a const ref for the in-param

chrome/browser/extensions/test_extension_environment.cc

Index: chrome/browser/extensions/test_extension_environment.cc
diff --git a/chrome/browser/extensions/test_extension_environment.cc b/chrome/browser/extensions/test_extension_environment.cc
index f8478fcbd9e66bc174d7e77d8c7df382dd2cc45d..6914ab089a2f568170733642275a23b6e30c2db2 100644
--- a/chrome/browser/extensions/test_extension_environment.cc
+++ b/chrome/browser/extensions/test_extension_environment.cc
@@ -41,7 +41,7 @@ scoped_ptr<base::DictionaryValue> MakeExtensionManifest(
     manifest->MergeDictionary(manifest_extra_dict);
   } else {
     std::string manifest_json;
-    base::JSONWriter::Write(&manifest_extra, &manifest_json);
+    base::JSONWriter::Write(manifest_extra, &manifest_json);
     ADD_FAILURE() << "Expected dictionary; got \"" << manifest_json << "\"";
   }
   return manifest;