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

extensions/common/value_builder.cc

Index: extensions/common/value_builder.cc
diff --git a/extensions/common/value_builder.cc b/extensions/common/value_builder.cc
index 3d8c2890f614f526d1bd8c9b7b8c82572b46ff83..4011e702ac270f33bc8a15a8999d18a4aafaf040 100644
--- a/extensions/common/value_builder.cc
+++ b/extensions/common/value_builder.cc
@@ -20,7 +20,7 @@ DictionaryBuilder::~DictionaryBuilder() {}
 std::string DictionaryBuilder::ToJSON() const {
   std::string json;
   base::JSONWriter::WriteWithOptions(
-      dict_.get(), base::JSONWriter::OPTIONS_PRETTY_PRINT, &json);
+      *dict_, base::JSONWriter::OPTIONS_PRETTY_PRINT, &json);
   return json;
 }