Prevent duplicate content script injection defined in manifest.json (reland)

extensions/renderer/scripts_run_info.h

Index: extensions/renderer/scripts_run_info.h
diff --git a/extensions/renderer/scripts_run_info.h b/extensions/renderer/scripts_run_info.h
index 6156eeb99be77ce74a67601e6cbaf8dda378e470..6eedac69a9eade0c05ed1c6daf9ac23b02cbca22 100644
--- a/extensions/renderer/scripts_run_info.h
+++ b/extensions/renderer/scripts_run_info.h
@@ -38,6 +38,8 @@ struct ScriptsRunInfo {
   size_t num_blocking_js;
   // A map of extension ids to executing script paths.
   ExecutingScriptsMap executing_scripts;
+  // A map of extension ids to injected stylesheet paths.
+  ExecutingScriptsMap injected_stylesheets;
   // The elapsed time since the ScriptsRunInfo was constructed.
   base::ElapsedTimer timer;