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Chromium Weekly Digest

Week 9 of 2026 (2026-02-25 to 2026-02-27)

Chromium Weekly: 2026 Week 9

Overview

This week's summary covers 1520 relevant commits out of 2116 total across 3 days. The week was defined by an exceptionally high volume of breaking changes, most notably the complete removal of the base::VariantMap utility container. Major new features landed, including the CSS contrast-color() function, while significant refactoring continued in the Remoting and ChromeOS components.

Major Breaking Changes

  • ⚠️ BREAKING BREAKING CHANGE The core utility container base::VariantMap and its header have been completely removed from the codebase. Downstream code must migrate to alternatives like absl::flat_hash_map or base::Value::Dict. (e3feeef)
  • ⚠️ BREAKING BREAKING CHANGE The Remoting component's public signaling API was refactored across several commits, replacing the generic jingle_xmpp::XmlElement with strongly-typed JingleMessage structures. This requires significant updates for clients of the remoting API. (39a36d8) (8e18de6) (ada63d3) (5f24c3d)
  • ⚠️ BREAKING BREAKING CHANGE The pure virtual method AcceptLanguages() has been removed from the core blink::ChromeClient interface, breaking embedders with custom implementations. (f8298ee)
  • ⚠️ BREAKING BREAKING CHANGE The chrome.serial API has been removed from Windows, Mac, and Linux, restricting its availability to ChromeOS only. Extensions relying on this API on desktop platforms will no longer function. (f39e3b6)
  • ⚠️ BREAKING BREAKING CHANGE Numerous API signatures were changed across the UI and content layers, including views::WebView::TakeCrashedOverlayView, TabListInterfaceObserver methods, and content::StoragePartition::ClearData, requiring embedders to update their implementations. (ff0a873) (8cdbdb6) (76d46af)
  • ⚠️ BREAKING BREAKING CHANGE The promise returned by the JavaScript methods element.scroll() and element.scrollTo() now resolves at the end of a smooth scroll animation, not immediately. This may break web applications that rely on the previous immediate-resolution behavior. (52379f7)

Web Platform & Blink

  • The CSS contrast-color() function has been implemented, allowing developers to programmatically select a color that maintains a minimum contrast ratio against a base color. (24d3ad2)
  • Foundational work has begun on a new filter attribute for <input> elements, which will allow them to be connected to a <select listbox> to create advanced combobox-like controls. (f584ce2)
  • CSS pseudo-elements ::after, ::before, and ::marker are now hit-testable and can receive hover effects, enabling more interactive use cases without extra DOM elements. (a433dd0)
  • The Event Timing architecture was significantly simplified by assigning interaction IDs synchronously and removing renderer-side buffering, improving the robustness of performance metrics. (d56215f)

UI & Features

  • The Task Manager refresh is complete. The feature is now enabled by default, and the old native macOS implementation has been deleted in favor of the cross-platform WebUI version. (5c16bf4)
  • Device Bound Sessions are now enabled by default on Windows, strengthening session security by binding cookies to the device without requiring an Origin Trial. (067236d)
  • The chrome.sessions API has been extended to desktop Android, allowing extensions to query and restore recently closed tabs and sessions. (286bcb3)
  • A new preference and extensions API, autofill.other_datatypes_enabled, have been added to give users and extensions more granular control over different autofill data types. (a64e731) (0de8cdc)

Android

  • ⚠️ BREAKING BREAKING CHANGE Support for Trusted Web Activities (TWA) and Progressive Web Apps (PWA) has been temporarily disabled in desktop mode due to crashes, representing a major behavioral change for apps relying on this functionality. (0ad6047)
  • ⚠️ BREAKING BREAKING CHANGE The public Android WebView API getDefaultUserAgent is now asynchronous and no longer blocks on Chromium initialization, which may impact embedders relying on the previous synchronous behavior. (077ae35)
  • Site Isolation is now always enabled for Android Desktop mode via the new kSitePerProcessForDesktopAndroid feature, significantly improving security for that form factor. (b37ddcc)

ChromeOS & Ash

  • ⚠️ BREAKING BREAKING CHANGE Multiple public APIs were modified as part of an ongoing migration from mojom to native C++, including ash::CaptureModeDelegate and crosapi::mojom::SearchResult, breaking custom implementations. (3cced2e) (4c90f1f)
  • The internal architecture for Video Conferencing was simplified by removing the VideoConferenceClientWrapper and its associated crosapi IPC layer. (2079ad0)

Core & Internals

  • The IndexedDB SQLite backend now uses idle time to perform maintenance tasks like checkpointing and trimming memory, improving overall performance and reliability. (5aad9e8)
  • As part of ongoing modularization, clipboard-related code was extracted from //chrome/browser into a new, more focused //chrome/browser/clipboard component. (150bd48)
  • The third-party zlib library was updated to version 1.3.2. (26c29f1)
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