GitLab

MediaClient::RequestCaptureState() was failing because chrome
does not have access to ash::SessionStateDelegate and ash::
ShellContentState.

1. Changed places that used ash::SessionStateDelegate to use
UserManager.

2. Changed places that used ash::ShellContentState to use
ChromeShellContentState. Right now the only places in ash that
use ash::ShellContentState are in tests so maybe we can move
ShellContentState to chrome completely in the future.

3. Changed MultiProfileMediaTrayItem and TrayUser in ash to
use SessionController to get the number of logged in users.

BUG=676091
TEST=ash_unittests

Review-Url: https://codereview.chromium.org/2615663002
Cr-Commit-Position: refs/heads/master@{#442679}