Intent to Ship: Data URL MIME Type Parameter Preservation

[Helmut Januschka]

Contact emails

hjanu...@gmail.com

Explainer

https://chromium-review.googlesource.com/c/chromium/src/+/7135039

Specification

https://fetch.spec.whatwg.org/#data-url-processor

Summary

Preserve MIME type parameters (e.g., charset, boundary) in data URL Content-Type headers per the Fetch Standard. CL: https://chromium-review.googlesource.com/c/chromium/src/+/7135039

Blink component

Blink>Network>FetchAPI

Web Feature ID

fetch

Motivation

Currently, Chromium only extracts the charset parameter from data URLs and discards other MIME type parameters. Per the Fetch Standard, data URL MIME type parameters should be preserved in the Content-Type header. For example: - data:text/plain;a=b,X should return Content-Type: text/plain;a=b - data:;charset=" x",X should return Content-Type: text/plain;charset=" x" This change brings Chromium into compliance with the Fetch Standard and improves web compatibility with other browsers. Spec: https://fetch.spec.whatwg.org/#data-url-processor

Initial public proposal

https://chromium-review.googlesource.com/c/chromium/src/+/7135039

TAG review

No information provided

TAG review status

Not applicable

Risks

Interoperability and Compatibility

No information provided

Gecko: Positive

WebKit: Positive

Web developers: Positive

Other signals:

WebView application risks

Does this intent deprecate or change behavior of existing APIs, such that it has potentially high risk for Android WebView-based applications?

No information provided

Debuggability

No information provided

Will this feature be supported on all six Blink platforms (Windows, Mac, Linux, ChromeOS, Android, and Android WebView)?

No

Is this feature fully tested by web-platform-tests?

Yes
external/wpt/fetch/data-urls/processing.any.html

Flag name on about://flags

No information provided

Finch feature name

DataUrlMimeTypeParameterPreservation

Rollout plan

(RARE) Experiment users ramp up over time

Requires code in //chrome?

False

Tracking bug

https://issues.chromium.org/issues/40487194

Estimated milestones

Shipping on desktop	146
Shipping on Android	146

Anticipated spec changes

Open questions about a feature may be a source of future web compat or interop issues. Please list open issues (e.g. links to known github issues in the project for the feature specification) whose resolution may introduce web compat/interop risk (e.g., changing to naming or structure of the API in a non-backward-compatible way).

No information provided

Link to entry on the Chrome Platform Status

https://chromestatus.com/feature/4874471565557760?gate=6595063650058240

This intent message was generated by Chrome Platform Status.

[Dan Clark]

> Gecko: Positive

> WebKit: Positive

Should these say Shipped/Shipping?  Firefox and Safari pass the WPT: https://wpt.fyi/results/fetch/data-urls?label=master&label=stable&aligned&q=fetch%2Fdata-urls%2Fprocessing.any.html

> Will this feature be supported on all six Blink platforms (Windows, Mac, Linux, ChromeOS, Android, and Android WebView)?

> No

Should this be Yes? In a quick scan of the CL I didn't see anything scoping this to a particular platform(s).

-- Dan

[Helmut Januschka]

@dan - updated, sorry

[Dan Clark]

Thanks! I see in the ChromeStatus entry that "Supported on all platforms" is now "Yes", but the Firefox and Safari positions still show Positive. Could you confirm these should be Shipped/Shipping or do those browsers not yet fully support the behavior we intend to ship?

Thanks,

Dan

[Daniel Bratell]

LGTM1 assuming they are shipping.

/Daniel

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[Vladimir Levin]

LGTM2 with the same assumption

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[Dan Clark]

LGTM3 with the same assumption.

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[Helmut Januschka]

thank you, still all the paperwork sometimes brings my weakness to light :) 

for sure, others are shipping: https://wpt.fyi/results/fetch/data-urls/processing.any.sharedworker.html?label=experimental&label=master&aligned this was my initial motivation to adress it, getting chromium green.

just failed when filing the I2S, updated rn.

cheers,