Refactoring: de-couple Extensions from "script injection System" [render side]:3

extensions/renderer/user_script_set_manager.cc

Index: extensions/renderer/user_script_set_manager.cc
diff --git a/extensions/renderer/user_script_set_manager.cc b/extensions/renderer/user_script_set_manager.cc
index 4379bab3e9d01a3957b9a79109b91e47604dba74..259434988872afe77729208faa9588128899baff 100644
--- a/extensions/renderer/user_script_set_manager.cc
+++ b/extensions/renderer/user_script_set_manager.cc
@@ -8,6 +8,7 @@
 #include "content/public/renderer/render_thread.h"
 #include "extensions/common/extension_messages.h"
 #include "extensions/renderer/dispatcher.h"
+#include "extensions/renderer/injection_host.h"

[Devlin, 2015/03/02 23:14:57]

Needed?

[Xi Han, 2015/03/03 00:03:31]

Done.

 #include "extensions/renderer/script_injection.h"
 #include "extensions/renderer/user_script_set.h"
 #include "ipc/ipc_message.h"
@@ -38,9 +39,9 @@ UserScriptSetManager::GetInjectionForDeclarativeScript(
     blink::WebFrame* web_frame,
     int tab_id,
     const GURL& url,
-    const Extension* extension) {
+    const std::string& extension_id) {
   UserScriptSet* user_script_set =
-      GetProgrammaticScriptsByExtension(extension->id());
+      GetProgrammaticScriptsByExtension(extension_id);
   if (!user_script_set)
     return scoped_ptr<ScriptInjection>();
 
@@ -49,8 +50,7 @@ UserScriptSetManager::GetInjectionForDeclarativeScript(
       web_frame,
       tab_id,
       UserScript::BROWSER_DRIVEN,
-      url,
-      extension);
+      url);
 }
 
 bool UserScriptSetManager::OnControlMessageReceived(