Moves Shell::CreateShelf() to WmShell

ash/test/test_session_state_delegate.cc

Index: ash/test/test_session_state_delegate.cc
diff --git a/ash/test/test_session_state_delegate.cc b/ash/test/test_session_state_delegate.cc
index 9d09bc8a852dc6d2c8ba9911dc29fa1a68fe7064..b625e295b0e007650baecac1174503ff2d64d0bb 100644
--- a/ash/test/test_session_state_delegate.cc
+++ b/ash/test/test_session_state_delegate.cc
@@ -175,7 +175,7 @@ void TestSessionStateDelegate::SetActiveUserSessionStarted(
   if (active_user_session_started) {
     user_manager_->SessionStarted();
     session_state_ = SESSION_STATE_ACTIVE;
-    Shell::GetInstance()->CreateShelf();
+    WmShell::Get()->CreateShelf();
     Shell::GetInstance()->UpdateAfterLoginStatusChange(LoginStatus::USER);
   } else {
     session_state_ = SESSION_STATE_LOGIN_PRIMARY;