[Extensions] Reduce string copy in renderer/ UserScript.

extensions/renderer/dispatcher.cc

Index: extensions/renderer/dispatcher.cc
diff --git a/extensions/renderer/dispatcher.cc b/extensions/renderer/dispatcher.cc
index 27979f922e75cd6199efcf077c8a6d43b2e94bf3..ab8c2e3494373de869c6986a0e5003a60d637cc5 100644
--- a/extensions/renderer/dispatcher.cc
+++ b/extensions/renderer/dispatcher.cc
@@ -582,10 +582,11 @@ void Dispatcher::DidCreateDocumentElement(blink::WebLocalFrame* frame) {
   if (extension && extension->is_extension() &&
       OptionsPageInfo::ShouldUseChromeStyle(extension) &&
       effective_document_url == OptionsPageInfo::GetOptionsPage(extension)) {
+    base::StringPiece extension_css =
+        ResourceBundle::GetSharedInstance().GetRawDataResource(
+            IDR_EXTENSION_CSS);
     frame->document().insertStyleSheet(
-        WebString::fromUTF8(ResourceBundle::GetSharedInstance()
-                                .GetRawDataResource(IDR_EXTENSION_CSS)
-                                .as_string()));
+        WebString::fromUTF8(extension_css.data(), extension_css.length()));
   }
 
   // In testing, the document lifetime events can happen after the render