Intent to Experiment: SoftNavigation performance entry

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Yoav Weiss

Nov 30, 2022, 9:01:46 AM11/30/22
to blink-dev

Contact emails



Not yet. I want to use the OT's feedback to assess the solution's viability.


Exposes the (experimental) soft navigation heuristics to web developers, using both PerformanceObserver and the performance timeline.

Blink component


TAG review

Not yet.

TAG review status

Not yet.


Interoperability and Compatibility

Gecko: No signal for now. Will file once feedback confirms viability.

WebKit: No signal for now. Will file once feedback confirms viability.

Web developers: Strong support!

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?


Goals for experimentation

I'm interested in gaining insights on the quality of the heuristic and how it compares to current heuristics employed by RUM providers or driven by framework- or app-specific knowledge. I'm also interested in knowing if developers find the correlation of various performance entries to their soft navigation ergonomic, and whether the emitted FP/FCP/LCP entries work well for them to evaluate the performance of their soft navigations.

Reason this experiment is being extended


Ongoing technical constraints



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


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


Flag name


Requires code in //chrome?


Tracking bug

Estimated milestones

OriginTrial desktop last112
OriginTrial desktop first109
OriginTrial Android last112
OriginTrial Android first109
OriginTrial webView last112
OriginTrial webView first109

Link to entry on the Chrome Platform Status

Links to previous Intent discussions

Intent to prototype:

This intent message was generated by Chrome Platform Status.

Mike Taylor

Nov 30, 2022, 9:16:26 AM11/30/22
to Yoav Weiss, blink-dev
LGTM to experiment from M109 to M112.
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Yoav Weiss

Jan 6, 2023, 5:14:11 AM1/6/23
to Mike Taylor, blink-dev
Update: We're bumping the experimentation from M109 to M110 (till M113), to align with partner timelines (and avoid them rediscovering bugs fixed in M109).

Yoav Weiss

Jun 14, 2023, 3:14:17 AM6/14/23
to Mike Taylor, blink-dev
I recently discovered that despite me asking for this to run till M113, the OT is running till M115.
The reason I haven't "renewed" the OT after M113 is that lined-up partners took a particularly long time to add support, which resulted in practically no-use for the OTed API (beyond a very small number of origins - Google-only link).

Now I'm interested in renewing the OT for M115, but wondered if the fact that the OT wasn't effectively used on M113-M114 (nor before, tbh) could be considered as a gap in the OT, and hence the renewal won't be considered as extending beyond the 6 milestone initial limit.  Thoughts?

Mike Taylor

Jun 14, 2023, 11:57:31 AM6/14/23
to Yoav Weiss, blink-dev

LGTM to keep going until M115.

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