chromeos: Remove AshTestBase::SupportsMultipleDisplays

ash/wm/window_state_unittest.cc

Index: ash/wm/window_state_unittest.cc
diff --git a/ash/wm/window_state_unittest.cc b/ash/wm/window_state_unittest.cc
index c5eff758c597a560c5a9d352535eed8036fc4b86..c37d8c2946debc18736d0d8b34f43bc7c528521b 100644
--- a/ash/wm/window_state_unittest.cc
+++ b/ash/wm/window_state_unittest.cc
@@ -65,9 +65,6 @@ INSTANTIATE_TEST_CASE_P(
 // Test that a window gets properly snapped to the display's edges in a
 // multi monitor environment.
 TEST_P(WindowStateTest, SnapWindowBasic) {
-  if (!SupportsMultipleDisplays())
-    return;
-
   UpdateDisplay("0+0-500x400, 0+500-600x400");
   const gfx::Rect kPrimaryDisplayWorkAreaBounds =
       display::Screen::GetScreen()->GetPrimaryDisplay().work_area();