[tnsardesai]

Summary

Bumps Chrome for Testing (and the matching ChromeDriver) from 152.0.7977.42 to 155.0.8059.84 in both the headful and headless images. That is the same Chromium build the private images already ship. The WebMCP fixture README named the version its behaviour was verified on, so it now says 155.0.8059.84.

The two Chromium 154 behaviour changes this bump depends on are already handled on main by #458: the headless PATCH /display viewport override being cleared when its CDP session detaches, and the chrome://extensions Developer mode toggle changing from role=button to role=switch. This PR is rebased onto main, so it no longer carries those changes.

Runtime dependencies

Between 152 and 155.0.8059.79 the only deb.deps change was the libglib2.0-0 minimum, from >= 2.39.4 to >= 2.49.3. Ubuntu 22.04 ships 2.72, so neither image needs new packages. .84 is a patch release on the same branch; the image builds and e2e below run on it.

Validation

• Both Chrome for Testing archives for 155.0.8059.84 (chrome-linux64, chromedriver-linux64) exist.
• CI on this head (run 41011525875): both images built from these Dockerfiles, and test-server-e2e passed against them with no failures, including the three headless resize scenarios, TestMV3ServiceWorkerRegistration and every WebMCP subtest. test-server-unit failed on the first attempt with a data race in TestReapplyBrowserLocationAfterRestart (a cleanup stub racing the background location reconcile goroutine); it doesn't involve Chromium, and it passed on rerun.
• Earlier, on 155.0.8059.79 (before the rebase): CI passed, and locally the headless e2e set passed, including all WebMCP subtests, the headless resize scenarios and TestMV3ServiceWorkerRegistration. I didn't rerun the local set on .84.

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Note

Medium Risk
Upgrading the browser runtime affects all automation and e2e behavior; risk is mitigated by CI validation but regressions in CDP, extensions, or WebMCP could still surface outside tested paths.

Overview
Bumps the pinned Chrome for Testing build (and matching ChromeDriver) from 152.0.7977.42 to 155.0.8059.84 in both the headful and headless Docker images via CHROME_VERSION; the download and install steps are unchanged.

Updates the WebMCP declarative fixture README so the documented Chromium version matches what the headless image now ships.

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[tnsardesai]

Picked rgarcia to review: touched the changed code in chromium-headful; 6 pending