LGTM3 On Wed, Dec 17, 2025 at 5:22 PM Rick Byers <[email protected]> wrote:
> LGTM2 > > Sounds like there might be some ongoing debate around the privacy vs. > utility tradeoff but I'm happy to see this ship and continue to iterate if > needed. > > > On Wed, Dec 17, 2025 at 10:12 AM Chris Harrelson <[email protected]> > wrote: > >> LGTM1 >> >> On Wed, Dec 10, 2025 at 10:52 AM Chromestatus < >> [email protected]> wrote: >> >>> *Contact emails* >>> [email protected], [email protected], [email protected] >>> >>> *Explainer* >>> >>> https://github.com/MicrosoftEdge/MSEdgeExplainers/blob/main/PerformanceNavigationTiming%20for%20User%20Agent%20Launch/explainer.md >>> >>> *Specification* >>> >>> https://w3c.github.io/navigation-timing/#sec-performance-timing-confidence >>> >>> *Design docs* >>> >>> >>> https://docs.google.com/document/d/1D6DqptsCEd3wPRsZ0q1iwVBAXXmhxZuLV-KKFI0ptCg/edit#heading=h.7nki9mck5t64 >>> >>> *Summary* >>> Web applications may suffer from bimodal distribution in page load >>> performance due to factors outside of the application’s control. For >>> example, when a user agent first launches in a “cold start” scenario, it >>> must perform many expensive initialization tasks that compete for system >>> resources. Browser extensions can also affect performance, since some >>> extensions run additional code on every page you visit, increasing CPU >>> usage and slowing response times. Likewise, when a machine is already busy >>> with intensive tasks, web pages may load more slowly as a result. In these >>> scenarios, content the web app attempts to load will be in competition with >>> other work happening on the system. This makes it difficult to detect if >>> performance issues exist within web applications themselves, or because of >>> external factors. Teams we have worked with have been surprised at the >>> difference between real-world dashboard metrics and what they observe in >>> page profiling tools. Without more information, it is challenging for >>> developers to understand if (and when) their applications may be >>> misbehaving or are simply being loaded in a contended period. A new >>> ‘confidence’ field on the PerformanceNavigationTiming object will enable >>> developers to discern if the navigation timings are representative for >>> their web application. >>> >>> *Blink component* >>> Blink>PerformanceAPIs>NavigationTiming >>> <https://issues.chromium.org/issues?q=customfield1222907:%22Blink%3EPerformanceAPIs%3ENavigationTiming%22> >>> >>> *Web Feature ID* >>> Missing feature >>> >>> *Motivation* >>> When a user agent first launches (a "cold start" scenario), it must >>> perform many expensive initialization tasks that compete for resources on >>> the system. Consequently, web applications may suffer from bimodal >>> distribution in page load performance. Content they attempt to load will be >>> in competition with other initialization work. This makes it difficult to >>> detect if performance issues exist within web applications themselves, or >>> because of a user-agent-generated condition of high resource contention. >>> This is particularly a pain point for pinned PWAs (Progressive Web Apps) >>> that will often require a cold start of the user agent, and teams we have >>> worked with have been surprised at the difference between real-world >>> dashboard metrics and what they observe in page profiling tools. Without >>> more information, it is challenging for developers to understand if (and >>> when) their applications may be misbehaving or are simply being loaded in a >>> contended period. To address this, we propose adding new information to >>> existing Web Performance APIs. >>> >>> *Initial public proposal* >>> >>> https://discourse.wicg.io/t/proposal-user-agent-launch-type-in-performancenavigationtiming/5875 >>> >>> *TAG review* >>> https://github.com/w3ctag/design-reviews/issues/878 >>> >>> *TAG review status* >>> Issues addressed >>> >>> *Origin Trial Name* >>> PerformanceNavigationTiming confidence >>> >>> *Chromium Trial Name* >>> PerformanceNavigationTimingConfidence >>> >>> *Origin Trial documentation link* >>> >>> https://github.com/MicrosoftEdge/MSEdgeExplainers/blob/main/PerformanceNavigationTiming%20for%20User%20Agent%20Launch/explainer.md >>> >>> *WebFeature UseCounter name* >>> kPerformanceNavigationTimingConfidence >>> >>> *Risks* >>> >>> >>> *Interoperability and Compatibility* >>> None. >>> >>> *Gecko*: No signal ( >>> https://github.com/mozilla/standards-positions/issues/1191) >>> >>> *WebKit*: No signal ( >>> https://github.com/WebKit/standards-positions/issues/469) >>> >>> *Web developers*: Positive ( >>> https://issues.chromium.org/issues/40255844#comment10) Positive >>> feedback from WebPerfWG. >>> https://w3c.github.io/web-performance/meetings/2025/2025-11-TPAC/index.html#h.jgi0mlvusons >>> >>> *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)?* >>> Yes >>> >>> *Is this feature fully tested by web-platform-tests >>> <https://chromium.googlesource.com/chromium/src/+/main/docs/testing/web_platform_tests.md>?* >>> Yes >>> >>> third_party/blink/web_tests/http/tests/misc/performance-navigation-timing-entry-confidence.tentative.html >>> >>> *Flag name on about://flags* >>> *No information provided* >>> >>> *Finch feature name* >>> PerformanceNavigationTimingConfidence >>> >>> *Rollout plan* >>> Will ship enabled for all users >>> >>> *Requires code in //chrome?* >>> True >>> >>> *Tracking bug* >>> https://bugs.chromium.org/p/chromium/issues/detail?id=1413848 >>> >>> *Estimated milestones* >>> Shipping on desktop 145 >>> Origin trial desktop first 136 >>> Origin trial desktop last 139 >>> Origin trial extension 1 end milestone 142 >>> DevTrial on desktop 135 >>> Shipping on Android 145 >>> Origin trial Android first 136 >>> Origin trial Android last 139 >>> DevTrial on Android 135 >>> Shipping on WebView 145 >>> >>> *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/5186950448283648?gate=6507865714458624 >>> >>> *Links to previous Intent discussions* >>> Intent to Prototype: >>> https://groups.google.com/a/chromium.org/g/blink-dev/c/o0F7nBKsgg0/m/bJSp3ekfAAAJ >>> Intent to Experiment: >>> https://groups.google.com/a/chromium.org/g/blink-dev/c/FYsfp0OsMko/m/WbhUrqSqAQAJ >>> Intent to Extend Experiment 1: >>> https://groups.google.com/a/chromium.org/d/msgid/blink-dev/6091e78f-7c77-4ed3-9559-eb660a14dfb7n%40chromium.org >>> >>> >>> This intent message was generated by Chrome Platform Status >>> <https://chromestatus.com>. >>> >>> -- >>> You received this message because you are subscribed to the Google >>> Groups "blink-dev" group. >>> To unsubscribe from this group and stop receiving emails from it, send >>> an email to [email protected]. >>> To view this discussion visit >>> https://groups.google.com/a/chromium.org/d/msgid/blink-dev/6939c150.710a0220.1d2509.07c8.GAE%40google.com >>> <https://groups.google.com/a/chromium.org/d/msgid/blink-dev/6939c150.710a0220.1d2509.07c8.GAE%40google.com?utm_medium=email&utm_source=footer> >>> . >>> >> -- >> You received this message because you are subscribed to the Google Groups >> "blink-dev" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to [email protected]. >> To view this discussion visit >> https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAOMQ%2Bw8XAjvGyfSt%3DJ4%3D4OMtPG5s%3DWqzTmwju0xn6s58e0tnpg%40mail.gmail.com >> <https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAOMQ%2Bw8XAjvGyfSt%3DJ4%3D4OMtPG5s%3DWqzTmwju0xn6s58e0tnpg%40mail.gmail.com?utm_medium=email&utm_source=footer> >> . >> > -- > You received this message because you are subscribed to the Google Groups > "blink-dev" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To view this discussion visit > https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAFUtAY_q%3Dx86iLt-BxLahVO%2BrMuu0SkUGEt1RDvUxC2nxs4VUQ%40mail.gmail.com > <https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAFUtAY_q%3Dx86iLt-BxLahVO%2BrMuu0SkUGEt1RDvUxC2nxs4VUQ%40mail.gmail.com?utm_medium=email&utm_source=footer> > . > -- You received this message because you are subscribed to the Google Groups "blink-dev" group. 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