Although similar to http://windowresizer.userecho.com/topic/674699-current-version-doesnt-resize-correctly/ I think this may be a separate issue. All of the viewport presets work except for HVGA 320 x 480. That one apparently sets the viewport width but fails to set viewport height, as the result is a window that is 320 pixels wide, but has no height, i.e. only the titlebar and location bar are visible.
I'm on Debian sid with Chromium 46.0.2490.71. I haven't yet tested on jessie, but it's likely the issue occurs there, too.
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