Hey,

We discussed this at API Owners today:
1. As Stephen mentioned, it would be nice if there was more support for 
this feature. Do you have partners or developers that are aware of this and 
are looking forward to using the feature?
2. In terms of approving this feature, we typically want the spec changes 
to exist in a stable forum (HTML, WICG, CSS, etc). Currently this is a spec 
PR that has concerns from other implementors, which isn't sufficient. 
Please let us know when the spec changes land in one of the accepted forums.

Thank you and let me know if you have questions!

Vlad

On Wednesday, December 11, 2024 at 9:31:21 AM UTC-5 Stephen Chenney wrote:

On Tue, Dec 10, 2024 at 11:08 PM Chromestatus <admin@cr-status.appspotmail.
com> wrote:

Contact emails ale...@google.com 

Explainer https://github.com/explainers-by-googlers/expect-no-linked-
resources 
https://explainers-by-googlers.github.io/expect-no-linked-resources 

Specification https://github.com/whatwg/html/pull/10718 

Summary 

The expect-no-linked-resources configuration point in Document Policy 
allows a document to hint to the user agent to better optimize its loading 
sequence, such as not using the default speculative parsing behavior. User 
Agents have implemented speculative parsing of HTML to speculatively fetch 
resources that are present in the HTML markup, to speed up page loading. 
For the vast majority of pages on the Web that have resources declared in 
the HTML markup, the optimization is beneficial and the cost paid in 
determining such resources is a sound tradeoff. However, the following 
scenarios might result in a sub-optimal performance tradeoff vs. the 
explicit time spent parsing HTML for determining sub resources to fetch: * 
Pages that do not have any resources declared in the HTML. * Large HTML 
pages with minimal or no resource loads that could explicitly control 
preloading resources via other preload mechanisms available. 
`expect-no-linked-resources` Document-Policy hints the User Agent that it 
may choose to optimize out the time spent in such sub resource 
determination.


Blink component Blink 
<https://issues.chromium.org/issues?q=customfield1222907:%22Blink%22> 

TAG review https://github.com/w3ctag/design-reviews/issues/1014 

TAG review status Pending 

Risks 


Interoperability and Compatibility 

Gecko has its speculative parsing pass integrated into document parser and 
hypothesizes that it might not have any benefit by adopting this standard. 
WebKit's stance is that it might want to invest in Gecko's architecture 
wrt. speculative parsing vs. receiving a hint from the web developer to 
optimize the hint. Thus this feature might not become interoperable. We 
believe that it is worth proceeding anyways, as our experimentation with 
parsing architectures suggests that there is a real tradeoff here that 
cannot be solved without a web developer hint. As a document-policy hint, 
the interoperability cost of this not being implemented everywhere is low: 
its presence will only cause small differences in speculative parsing 
timing, which are already permitted by the HTML Standard. Similarly, the 
compatibility risk of this feature is low. If we were to eventually remove 
it, it would be very hard for web developers to notice. More of the 
discussions at the HTML standard pull request and the subsequent WHATNOT 
meeting notes below: https://github.com/whatwg/html/pull/10718 WHATNOT 
discussion minutes: https://github.com/whatwg/html/issues/10709 
https://github.com/whatwg/html/issues/10720 https://github.com/whatwg/
html/issues/10734 https://github.com/whatwg/html/issues/10750


Did you consider investing in Gecko's architecture? In other words, is this 
introducing a non-compatible web feature to address a chromium-specific 
software design choice?
 


*Gecko*: Negative (https://github.com/whatwg/html/pull/10718) Gecko has its 
speculative parsing pass integrated into document parser and hypothesizes 
that it might not have any benefit by adopting this standard. Given their 
comments on the pull requests and at WHATNOT meetings, we believe it's not 
necessary to file for a formal standards position. 

*WebKit*: Negative (https://github.com/whatwg/html/pull/10718) Given their 
comments on the pull requests and at WHATNOT meetings, we believe it's not 
necessary to file for a formal standards position. 

*Web developers*: Positive (https://docs.google.com/document/d/
1VhztmwDUz40sb2HEBfNJjplva8hXgAP3C6qlyTFbfr0/edit?tab=t.0#
heading=h.9mt7t18673oo)


Do you have more than 1 piece of public web developer feedback, ideally 
from a non-Google product?



*Other signals*: 

Ergonomics 

None. The feature is opted-in on a per-response basis by a page that does 
not benefit from speculative parsing, and is off by default.


Activation 

None. 


Security 

This feature does not change security risks.


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?

None


Debuggability 

The feature usage, i.e., opt-in by the page, will be visible under page 
Headers in network panel of the DevTools interface. 


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

Is this feature fully tested by web-platform-tests 
<https://chromium.googlesource.com/chromium/src/+/main/docs/testing/web_platform_tests.md>
? Yes 

https://github.com/web-platform-tests/wpt/pull/49617


Flag name on about://flags 

Finch feature name DocumentPolicyExpectNoEmbeddedResources 

Requires code in //chrome? False 

Tracking bug https://issues.chromium.org/issues/365632977 

Estimated milestones Shipping on desktop 133 Shipping on Android 133 Shipping 
on WebView 133 

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).
None 

Link to entry on the Chrome Platform Status https://chromestatus.com/
feature/5202800863346688?gate=5195231151259648 

Links to previous Intent discussions Intent to Prototype: 
https://groups.google.com/a/chromium.org/d/msgid/blink-dev/
00000000000050b3190621c328c4%40google.com 


This intent message was generated by Chrome Platform Status 
<https://chromestatus.com>. 

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