Update TestSessionStateDelegate to properly represen user sessions
Update TestSessionStateDelegate internal states to properly follow user session
state changes.
This is a replacement change for: https://codereview.chromium.org/
958133002/
The changes have been redone to remove the dependency on
user_manager::UserManager which is only available on Chrome OS builds.
TestSessionStateDelegate was using a series of booleans to represent various
states. It has been updated to user a TestUserManager for tracking user login
state, as well as updated to tracking the SessionState.
TEST=Ran ash_unittests, unit_tests, and TrayAccessibilityTest
BUG=459287
Review URL: https://codereview.chromium.org/
1125033002
Cr-Commit-Position: refs/heads/master@{#328679}