feat: Support response headers in File protocol handler

[dbkr]

Description of Change

This adds support for response headers to protocol.registerFileProtocol to match protocol.registerStreamProtocol.

My specific use case for this is to set a CSP for pages served from local content rather than HTTPS: setting the header by intercepting the request with the webRequest module doesn't work because URLRequestAsarJob doesn't call the network_delegate methods (see #16030). In any case, this seems like a more direct way of setting the header.

I've also changed how this works a little to make it more consistent (hopefully) with the other handlers (ie. convert the dict to a base::DictionaryValue and use base::DictionaryValue::GetFoo()).

Note that I've documented this in the text as the callback param in the list has filePath as a string. This could be changed so the callback taking an object is in the main docs: I'm happy to make this change.

Stakeholders: @zcbenz & @paulcbetts appear to have last made major changes here. cc @MarshallOfSound as you kindly helped on the issue I filed.

Test failures don't appear to be related to my changes: one of them is:

AssertionError: exit signal should be null, if you see this please tag @MarshallOfSound: expected 'SIGSEGV' to equal null

(so, cc @MarshallOfSound)

Checklist

• PR description included and stakeholders cc'd
• npm test passes: failures appear unrelated to my changes
• tests are changed or added
• relevant documentation is changed or added
• PR title follows semantic commit guidelines

Release Notes

Notes: Add response header support to protocol.registerFileProtocol to match protocol.registerStreamProtocol.

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[ckerr]

Premise and tests LGTM. Thanks for the patch!

Once the deprecated API use is changed I'm 👍 on this

[ckerr]

This introduces a minor regression of going back to deprecated API:

// DEPRECATED, use Value::FindPath(path) and Value::GetString() instead.
bool GetString(StringPiece path, std::string* out_value) const;

Could you keep the previous FindKeyOfType implementation?

[dbkr]

Ah, hadn't noticed that was deprecated. Fixed!

[codebytere]

👍 following your latest changes!

[ckerr]

Thanks!

[release-clerk]

Release Notes Persisted

Add response header support to protocol.registerFileProtocol to match protocol.registerStreamProtocol.

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