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..8865a587ba6452fca676fd1aa637a3b36389d404 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"
 #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 InjectionHost* injection_host) {
   UserScriptSet* user_script_set =
-      GetProgrammaticScriptsByExtension(extension->id());
+      GetProgrammaticScriptsByExtension(injection_host->id().id());
   if (!user_script_set)
     return scoped_ptr<ScriptInjection>();
 
@@ -50,7 +51,7 @@ UserScriptSetManager::GetInjectionForDeclarativeScript(
       tab_id,
       UserScript::BROWSER_DRIVEN,
       url,
-      extension);
+      injection_host);
 }
 
 bool UserScriptSetManager::OnControlMessageReceived(