Migrate call sites LoginDisplayHostImpl::default_host to LoginDisplayHost.

chrome/browser/chromeos/login/login_browsertest.cc

Index: chrome/browser/chromeos/login/login_browsertest.cc
diff --git a/chrome/browser/chromeos/login/login_browsertest.cc b/chrome/browser/chromeos/login/login_browsertest.cc
index 3e8ef591f920c535d92a3c75a76f02d8a2660b32..d1d248e77b4b97ae1fc1a4fb634a5a658daffe51 100644
--- a/chrome/browser/chromeos/login/login_browsertest.cc
+++ b/chrome/browser/chromeos/login/login_browsertest.cc
@@ -228,8 +228,8 @@ IN_PROC_BROWSER_TEST_F(LoginCursorTest, CursorHidden) {
   EXPECT_TRUE(ui_test_utils::SendMouseMoveSync(gfx::Point()));
   EXPECT_TRUE(ash::Shell::GetInstance()->cursor_manager()->IsCursorVisible());
 
-  base::MessageLoop::current()->DeleteSoon(
-      FROM_HERE, LoginDisplayHostImpl::default_host());
+  base::MessageLoop::current()->DeleteSoon(FROM_HERE,
+                                           LoginDisplayHost::default_host());
 
   TestSystemTrayIsVisible();
 }