I want to create the chrome extension that will past the static gif by URL(for example this) after loading the "compose" (new email) window. As I understand correctly, I need to use only content.js
I'm trying to find some info on how to do this for a long time and found this decision. But when I insert this code into my content.js(almost empty) it writes to me that DriveApp is not defined. So, as I understand I need to include something for using this class, but I can`t find correct info on how to do it.
Also, I think that it could be some easier decision to create the extension which will add static gif by URL after loading compose window if(document.querySelector('.AD'))
I am not good at this, so I hope will be glad of any help, especially a complete solution :)