Don't let rounding prematurely influence document size when printing

Don't round away subpixel values when they can still make a difference to the
size of the document. We convert back and forth between different DPIs so we
can lose a pixel or two along the way if we don't retain subpixel values to
the end.

BUG=467579

Review-Url: https://codereview.chromium.org/2116283002
Cr-Commit-Position: refs/heads/master@{#409469}
17 files changed