Add util method to update ArchiveAnalyzerResults for a single file

This CL breaks out the code that inspects an individual file within a
ZIP archive. This will be shared between the ZIP and RAR inspection,
when RAR files begin doing content inspection.

Bug: 909778
Change-Id: I7acf1cabd472f112f2ed7c31735688cae7a6d122
Reviewed-on: https://chromium-review.googlesource.com/c/1354103
Commit-Queue: Daniel Rubery <drubery@chromium.org>
Reviewed-by: Brian White <bcwhite@chromium.org>
Reviewed-by: Jay Civelli <jcivelli@chromium.org>
Reviewed-by: Varun Khaneja <vakh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#612799}
7 files changed