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Explainer https://github.com/whatwg/html/issues/11070 Specification None Summary We propose to add a new render blocking token full-frame-rate to the blocking attributes. When the renderer is blocked with the full-frame-rate token, the renderer will work at a lower frame rate so as to reserve more resources for loading. An example use case of the proposed API will be: The web page contains an element <link rel="expect" href="#critical-content" blocking="full-frame-rate"/> in the page head. After parsing this element, the renderer will work at an implementation-specific lower frame rate. After the #critical-content element is parsed, the renderer will restore its frame rate. It is worth noting that the frame rate instructions will be informative. The browser may decide to lower the frame rate before parsing a blocking element. For instance, the frame rate may be lowered at the very beginning of the loading phase. On the other hand, the browser may also decide to restore the frame rate before the frame rate blocking element list gets empty. For instance, the frame rate may be restored after a timeout or certain user interactions. Blink component Blink>Compositing <https://issues.chromium.org/issues?q=customfield1222907:%22Blink%3ECompositing%22> TAG review None TAG review status Pending We plan to run a quick test so as to verify the loading performance impact on certain sites. Field experiments on the beta channel do not show significant loading performance improvement so the feature may not be shipped at all. Thus, we'll delay requesting TAG review and other browser signals until we are more confident in the feature's value. Risks Interoperability and Compatibility None The API is introducing an informative signal to lower the frame rate during loading. The browsers not implementing the feature will simply ignore the element. The behavior will not change on these browsers. We consider the risk to be minimal. Gecko: No signal WebKit: No signal Web developers: No signals 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? None Goals for experimentation We would like to verify the impact of the frame rate blocking API on the loading performance. The loading performance changed will be measured by the UMA WebVitals.FirstContentfulPaint4 and WebVitals.LargestContentfulPaint3. The developers can also measure the impact by collecting latency data in the page loading process. Ongoing technical constraints None Debuggability None Will this feature be supported on all six Blink platforms (Windows, Mac, Linux, ChromeOS, Android, and Android WebView)? No Yes Is this feature fully tested by web-platform-tests <https://chromium.googlesource.com/chromium/src/+/main/docs/testing/web_platform_tests.md> ? No Acquiring the frame rate during page loading in javascript turned out to be very difficult and the result is unpredictable on different platforms. Thus it is hard to add a test to verify that the frame rate is really lowered during loading in web tests. Flag name on about://flags None Finch feature name RenderBlockingFullFrameRate Requires code in //chrome? False Tracking bug https://crbug.com/397832388 Launch bug https://launch.corp.google.com/launch/4385256 Estimated milestones Origin trial desktop first 139 Origin trial desktop last 144 Origin trial Android first 139 Origin trial Android last 144 Origin trial WebView first 139 Origin trial WebView last 144 Link to entry on the Chrome Platform Status https://chromestatus.com/feature/5207202081800192?gate=5073049818497024 Links to previous Intent discussions Intent to Prototype: https://groups.google.com/a/chromium.org/d/msgid/blink-dev/67c7dfbb.2b0a0220.1efd8e.0902.GAE%40google.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 blink-dev+unsubscr...@chromium.org. To view this discussion visit https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAJQw1NxZLiK3FW6ny%2BYuyF%3D%3DJW7WFEeXsLoiOuzeoUXnk171Rg%40mail.gmail.com.
