Reland "Remove ContrastAdjust()."

Original change's description:
> Revert "Remove ContrastAdjust()."
> 
> This reverts commit 53d443f042b590ae2d920def16bc9daf66f8427d.
> 
> Reason for revert: Breaks PDFToPWGRasterBrowserTest
> 
> Original change's description:
> > Remove ContrastAdjust().
> > 
> > This post-processing increased the contrast of scaled-down features -
> > mainly lines and fonts, relative to the background. The effect does not
> > improved readability and in some cases makes the scaled-down version
> > look like a different document at a glance. Text that is normal
> > weight appears bold when scaled down in these cases.
> > 
> > Change-Id: I2544d45e2bcec25d6742d2a60c1316d8df08cce1
> > Reviewed-on: https://pdfium-review.googlesource.com/15471
> > Commit-Queue: Henrique Nakashima <hnakashima@chromium.org>
> > Reviewed-by: dsinclair <dsinclair@chromium.org>
> 
> TBR=bungeman@chromium.org,dsinclair@chromium.org,hnakashima@chromium.org
> 
> # Not skipping CQ checks because original CL landed > 1 day ago.
> 
> Change-Id: I7f61650bc6d917b3c6640da60f3f740ef4498de0
> Reviewed-on: https://pdfium-review.googlesource.com/16970
> Commit-Queue: Henrique Nakashima <hnakashima@chromium.org>
> Reviewed-by: Henrique Nakashima <hnakashima@chromium.org>

TBR=bungeman@chromium.org,dsinclair@chromium.org,hnakashima@chromium.org

Change-Id: I77d4377d30908d1e2d4dc842300a761072a5fbd4
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://pdfium-review.googlesource.com/16990
Reviewed-by: Henrique Nakashima <hnakashima@chromium.org>
Commit-Queue: Henrique Nakashima <hnakashima@chromium.org>

0 files changed, 0 insertions, 0 deletions