Chrome 151 Ships the usermedia Element and Declarative Slot Assignment

Chrome 151 went stable on July 28, and the standout is <usermedia>, a browser-controlled element for starting and interacting with camera and microphone streams. You drop it into the DOM and the browser owns the permission flow as platform behavior, not app logic.

The design centers on user intent. A click on the element is the clear, intentional signal before any permission prompt appears, and the recovery path after a previous denial is straightforward. The browser handles the prompt, the denial, and the retry. You stop maintaining permission-state state machines per app.

The second feature targets web components: shadowrootslotassignment on <template> gives declarative shadow roots manual slot assignment, previously imperative-only through attachShadow({ slotAssignment: "manual" }). If you build components with declarative shadow DOM, you move slot setup into markup and delete the constructor code that configured it.

Two more items earn a look. textStream() on Request, Response, and Blob streams text without piping through a TextDecoderStream, which cuts a decode layer from anything that processes responses incrementally, from chat UIs to log tailers. The soft-navigation and interaction-contentful-paint performance entries give SPA route changes real browser-level timing instead of your analytics wrapper's best guess. Housekeeping: XML parsing moves to a Rust implementation, and macOS 12 support drops, so CI images need macOS 13 or newer. Both headline features push web components toward declarative, framework-less patterns.