Rework some UserScriptLoader logic in preparation to removing UserScript copy.

extensions/browser/web_ui_user_script_loader.cc

Index: extensions/browser/web_ui_user_script_loader.cc
diff --git a/extensions/browser/web_ui_user_script_loader.cc b/extensions/browser/web_ui_user_script_loader.cc
index 2b018793e92bb5f3e2352f7ff6477f31b7e68055..23f48132ddddf0835a78eed9f2f169e0ac03b12d 100644
--- a/extensions/browser/web_ui_user_script_loader.cc
+++ b/extensions/browser/web_ui_user_script_loader.cc
@@ -48,7 +48,7 @@ WebUIUserScriptLoader::~WebUIUserScriptLoader() {
 }
 
 void WebUIUserScriptLoader::AddScripts(
-    const std::set<extensions::UserScript>& scripts,
+    const extensions::UserScriptList& scripts,
     int render_process_id,
     int render_view_id) {
   UserScriptRenderInfo info(render_process_id, render_view_id);