GitLab

Added an interface to the existing printing Mojo service for pdf N-up
Conversion for web content.  The service has two main functions:
NupPageConvert(): Convert N PDF pages to a N-up PDF.
NupDocumentConvert(): Convert a PDF document to a N-up PDF document.

In printing, 2-up, 3-up, or more generally N-up refers to a page
layout strategy in which multiple pages are composited onto a
single page.

Bug: 775999
Change-Id: I7c3b78a6d7b2fdaaa3d67e456b6b3b624480897e
Reviewed-on: https://chromium-review.googlesource.com/1172100
Commit-Queue: Shirleen Lou <xlou@chromium.org>
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Reviewed-by: Lei Zhang <thestig@chromium.org>
Cr-Commit-Position: refs/heads/master@{#585097}