Inject javascript in an iframe using chrome extension
Yes, you can use content_scripts property in manifest.json like this:
"content_scripts": [{ "matches": ["http://*/*", "https://*/*"], "js": ["content_frame.js"], "all_frames": true}],By setting all_frames to true you will inject/include content_frame.js javascript file into top document and all iframes. In case you just need javascript injected in iframe but not in top document you can check inside your content_frame.js file like this:
if (parent === top) { // here you can put your code that will run only inside iframe}