When does a run_at: document_idle content script run?

Question

There are three options for running content scripts:

1. document_start - injected at the start of the
2. docume

Answer 1

According to the current Chromium source:

We try to run idle in two places: here and DidFinishLoad. DidFinishDocumentLoad() corresponds to completing the document's load, whereas DidFinishLoad corresponds to completing the document and all subresources' load. We don't want to hold up script injection for a particularly slow subresource, so we set a delayed task from here - but if we finish everything before that point (i.e., DidFinishLoad() is triggered), then there's no reason to keep waiting.

Translated into web developer speak that basically means…

document_idle scripts will run the earliest one of these things is true:

1. window.onload has fired
2. It's been 200ms since DOMContentLoaded has fired.

On typical pages, these scripts will likely run at #2.