Refactoring: de-couple Extensions from "script injection System" [render side] : 1

extensions/common/extension_messages.h

Index: extensions/common/extension_messages.h
diff --git a/extensions/common/extension_messages.h b/extensions/common/extension_messages.h
index aee505c44a9d4b8a71a52d1648c842b9b56a2ced..a84bb81a02a833947a4af47144ff7406aeb65ba4 100644
--- a/extensions/common/extension_messages.h
+++ b/extensions/common/extension_messages.h
@@ -135,6 +135,10 @@ IPC_STRUCT_BEGIN(ExtensionMsg_ExecuteCode_Params)
   // Whether the request is coming from a <webview>.
   IPC_STRUCT_MEMBER(bool, is_web_view)
 
+  // The script injection instance id of a <webview> if the request is comming
+  // from a <webview>; else, the default instance id (0).
+  IPC_STRUCT_MEMBER(int, instance_id)
+
   // Whether the caller is interested in the result value. Manifest-declared
   // content scripts and executeScript() calls without a response callback
   // are examples of when this will be false.