GitLab

Moving the manifest parsing and extension validation from the
Unpacker class to SandboxedUnpacker. As a result, all the extension
unpacking is done from the browser process and the Unpacker class is
removed.

The 2 remaining methods in unpacker.cc still used for unzipping the
extension have been moved to utility_handler.cc and the associated
tests renamed from unpacker_unittest.cc to utility_handler_unittest.cc.
The unzipping will also eventually be moved to the browser process at
which point utility_handler files will be removed as well.

Tbr: rockot@chromium.org
Bug: 800540
Change-Id: Ib286fa88edc96e4c186aba6e2ee1d9c2317efe84
Reviewed-on: https://chromium-review.googlesource.com/883967Reviewed-by: Ken Rockot <rockot@chromium.org>
Reviewed-by: Reilly Grant <reillyg@chromium.org>
Reviewed-by: Tom Sepez <tsepez@chromium.org>
Commit-Queue: Jay Civelli <jcivelli@chromium.org>
Cr-Commit-Position: refs/heads/master@{#532064}