[Extensions] Don't allow extensions to inject scripts into extension pages

extensions/renderer/script_injection.h

Index: extensions/renderer/script_injection.h
diff --git a/extensions/renderer/script_injection.h b/extensions/renderer/script_injection.h
index ccb4d1f3230ce23760096252daf02648462d6be8..14e34ae407235b77df585f3ffb6b66d65e993931 100644
--- a/extensions/renderer/script_injection.h
+++ b/extensions/renderer/script_injection.h
@@ -53,8 +53,7 @@ class ScriptInjection {
   ScriptInjection(scoped_ptr<ScriptInjector> injector,
                   content::RenderFrame* render_frame,
                   scoped_ptr<const InjectionHost> injection_host,
-                  UserScript::RunLocation run_location,
-                  int tab_id);
+                  UserScript::RunLocation run_location);
   ~ScriptInjection();
 
   // Try to inject the script at the |current_location|. This returns
@@ -117,9 +116,6 @@ class ScriptInjection {
   // The location in the document load at which we inject the script.
   UserScript::RunLocation run_location_;
 
-  // The tab id associated with the frame.
-  int tab_id_;
-
   // This injection's request id. This will be -1 unless the injection is
   // currently waiting on permission.
   int64 request_id_;