(In reply to lei.pero from comment #33)
> Yeah, but by setting 1 and using any other WM results in Chromium/Chrome
> being VSYNC-ed, [...]

With a compositing manager, tearing or not is up to that. 

> [...] i would call it mutter/clutter configuration bug [...]

vblank_mode is Mesa configuration overriding mutter's intent, so it cannot
reasonably be called that.

> plus it doesn't explain DRI2 behavior that follows same standard :).

It's probably just a happy accident that it works better according to your
criteria with DRI2.