Convert remaining StringToLowerASCII to ToLowerASCII

content/renderer/npapi/webplugin_impl.cc

Index: content/renderer/npapi/webplugin_impl.cc
diff --git a/content/renderer/npapi/webplugin_impl.cc b/content/renderer/npapi/webplugin_impl.cc
index bb42af96991053b25e8a0be9438f46e81242cf6e..8e8a1e96dc2e9f80fa00bc52047c8684dbc45b11 100644
--- a/content/renderer/npapi/webplugin_impl.cc
+++ b/content/renderer/npapi/webplugin_impl.cc
@@ -553,11 +553,11 @@ WebPluginImpl::WebPluginImpl(
       first_geometry_update_(true),
       ignore_response_error_(false),
       file_path_(file_path),
-      mime_type_(base::UTF16ToASCII(base::StringPiece16(params.mimeType))),
+      mime_type_(base::ToLowerASCII(base::UTF16ToASCII(
+          base::StringPiece16(params.mimeType)))),
       loader_client_(this),
       weak_factory_(this) {
   DCHECK_EQ(params.attributeNames.size(), params.attributeValues.size());
-  base::StringToLowerASCII(&mime_type_);
 
   for (size_t i = 0; i < params.attributeNames.size(); ++i) {
     arg_names_.push_back(params.attributeNames[i].utf8());