GitLab

Encapsulate ClearAllPreviewData() and SetPrintPreviewDataForIndex().

Change-Id: I0ad046aef0ffcf098cc783bc177a8597c1c973c5
Reviewed-on: https://chromium-review.googlesource.com/1188778
Commit-Queue: Lei Zhang <thestig@chromium.org>
Reviewed-by: Rebekah Potter <rbpotter@chromium.org>
Cr-Commit-Position: refs/heads/master@{#588269}