更改输入字段的最佳方法？

Am trying to create an extension that fill each input field(text,search,...) in any webpage with an icon when I click on it a drop down menu appears, Just like Lazarus from recovery icon or the google search by voice icon, I tried so many ways lately but nothing worked will :( Am trying to find a way that is suitable for all fields whatever their shape or sizeAm trying to create an extension that fill each