Upcoming Windows toolchain update to VS 2026 and SDK 26100.7705

[Devon Loehr]

We are about to land a CL that will update Chromium to build using the most recent windows tools, most notably Visual Studio 2026. For googlers building on corp devices, no action is needed -- the new tools will be picked up automatically by `gclient sync`.

For everyone else, please make sure your computer has the latest version of both Visual Studio and the windows SDK (10.0.26100.7705), which can be installed as a component of Visual Studio or from Microsoft's website.

As with previous toolchain updates, please wait 2 weeks after the CL lands before you begin relying on any new features -- this gives us time to detect any hidden issue and revert the update if necessary. During that time, we will continue to support VS 2022 and the old SDK version on a best-effort basis, but that support will end afterwards.

--Devon Loehr