tree 6413655293d841b3904780ed8248572c9e7c9b69
parent 3f39d5cc753905874d8d93bef94f857b8808f19e
author Alex Deymo <deymo@google.com> 1444677747 -0700
committer Alex Deymo <deymo@google.com> 1444855346 -0700

update_manager: Make Prefs Variable async.

The update_engine prefs, while stored in disk, are private daemon
values changed by the daemon only. There was a 5 minutes delay between
changing this value and the update policy checking it again, and there
was a log spam every 5 minutes due to policy re-evaluations.

This patch makes these Prefs-based variables async by implementing an
observer pattern in the PrefsInterface and makes these variables async.

Bug: chromium:367333
Test: Added uniittest. No more log spam every 5 minutes.

Change-Id: I8b3f7072cc87515972c9f5b1ddcc54b865ffe238