webRequest.onHeadersReceived does not lower case header names #880
Description
Was asked to create a ticket here for discussion by the Chromium team: https://issues.chromium.org/issues/447256830#comment2
The webRequest.onHeadersReceived listener returns an object with response headers, however, these headers seem to be case sensitive as the API returns them in whatever casing the server provides.
As per https://www.rfc-editor.org/rfc/rfc9110.html#section-5.1-3, headers are supposed to be case insensitive, so this can make it hard to detect certain header names. I ran into this using Electron when trying to intercept headers from web requests in my application (relevant Electron bug: github.com/electron/electron/issues/48365)
It might be a breaking change to do this, but I'm thinking it makes more sense to force the headers to return in all lowercase, such that it doesn't matter what the server sends.