Revert of Introduce SessionManager that will contain code to start user session on...

Revert of Introduce SessionManager that will contain code to start user session on Chrome OS (https://codereview.chromium.org/318853004/)

Reason for revert:
Appears to have broken the kiosk and auth browser tests in http://build.chromium.org/p/chromium.chromiumos/builders/Linux%20ChromiumOS%20Tests%20%28dbg%29%281%29/builds/30916

Original issue's description:
> Introduce SessionManager that will contain code to start user session on Chrome OS
>
> Move profile creation / session initialization (prefs/RLZ) as well as some of OAuth session init
> related code from LoginUtils to SessionManager. LoginUtils will temporarily implement
> SessionManager::Delegate interface till existing test coverage is migrated from LoginUtils interface.
> SessionManager will later use concept of UserSession (see design proposal at http://goto/cros-login-c14n).
>
> LoginUtils::OnPrepareProfile() is split into
> StartSession()
> --PreStartSession() - things like switching logging dest
> --CreateUserSession() - will eventually create UserSession instance
> --StartCrosSession() - notify cros::SessionManager
> --NotifyUserLoggedIn() - UserManager::UserLoggedIn()
> --PrepareProfile()
>
> PrepareProfile() - calls PM::CreateProfileAsync()
> --OnProfileCreated()
> ----InitProfilePreferences() - early initialization
> ----UserProfileInitialized()
> ------transfer signin profile auth date (cookies/proxy auth/certs)
> ------RestoreAuthSessionImpl() - OAuth2LoginManager::RestoreSession()
> ----FinalizePrepareProfile(()
> ------Own TPM (if it didn't happen for some reason)
> ------Notify SAML offline signin limiter
> ------Notify ProfileImpl
> ------chrome::NOTIFICATION_LOGIN_USER_PROFILE_PREPARED
> ------InitRLZ (for primary user)
>
>
> Minor cleanup
> * Unify DemoApp profile initialization flow with regular one
> * Don't pass display_email to LoginUtils::PrepareProfile
> * Move powerwash related prefs registration to ResetScreenHandler
> * Cleanup M31 migration code for |prefs::kProfileIsManaged| in LoginUtilsImpl::InitProfilePreferences()
>
> BUG=370175,276163
>
> Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=276626

TBR=antrim@chromium.org,bauerb@chromium.org,nkostylev@chromium.org
NOTREECHECKS=true
NOTRY=true
BUG=370175,276163

Review URL: https://codereview.chromium.org/328383003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@276760 0039d316-1c4b-4281-b951-d872f2087c98