GitLab

We need a ProcessManager to exist in order to load background
pages but like everything extension-related it is lazy created

Bug: b/73768170
Test: load extension at start verify background script prints occur


Change-Id: I63ccc58ee819ec0435646c296ceb0d7678c433cc
Reviewed-on: https://chromium-review.googlesource.com/959343Reviewed-by: Kevin Schoedel <kpschoedel@chromium.org>
Reviewed-by: Luke Halliwell <halliwell@chromium.org>
Commit-Queue: Albert Chaulk <achaulk@chromium.org>
Cr-Commit-Position: refs/heads/master@{#545851}