Properly set ShelfAlignment during login

ShelfLayoutManager has three methods from which the ShelfAlignment can be
applied. For supressed user sessions the shelf is forced to the bottom, however
this was only addressing locked screens, and adding new users.

When the first login occurs a different state transition takes place, where the
SessionState becomes active while the user session is still supressed.
ShelfLayoutManager was not applying alignment changes made during this time.

Update ShelfLayoutManager to unify the logic for overriding the user set
ShelfAlignment. Update this logic to account for having to apply alignment
during the initial login.

Manual testing was also done for: logging in; locking screen; unlocking screen;
adding a new user; switching users.

TEST=ShelfLayoutManagerTest.SideAlignmentInteractionWithLockScreen, ShelfLayoutManagerTest.SideAlignmentInteractionWithAddUserScreen, ShelfLayoutManagerTest.SideAlignmentInteractionWithLoginScreen
BUG=456199

Review URL: https://codereview.chromium.org/909293002

Cr-Commit-Position: refs/heads/master@{#316673}

0 files changed, 0 insertions, 0 deletions