Add extension handling to chrome_cleaner/ipc and chrome_cleaner/ui

R=csharp@chromium.org

Bug: 830892
Change-Id: Ib3157dc17c2e2c7738f6b2a6af7d88ed72eb4d33
Reviewed-on: https://chromium-review.googlesource.com/c/1338402
Reviewed-by: Chris Sharp <csharp@chromium.org>
Reviewed-by: Ken Rockot <rockot@google.com>
Commit-Queue: Joe Mason <joenotcharles@google.com>
Cr-Commit-Position: refs/heads/master@{#609001}
12 files changed