chromeos: Remove AshTestBase::SupportsMultipleDisplays

ash/wm/toplevel_window_event_handler_unittest.cc

Index: ash/wm/toplevel_window_event_handler_unittest.cc
diff --git a/ash/wm/toplevel_window_event_handler_unittest.cc b/ash/wm/toplevel_window_event_handler_unittest.cc
index 45e20807d2f25cebc334ee4322e037a73d5ee9ec..23aa801cdff39f3585313bc7d482e773b895dbad 100644
--- a/ash/wm/toplevel_window_event_handler_unittest.cc
+++ b/ash/wm/toplevel_window_event_handler_unittest.cc
@@ -814,9 +814,6 @@ TEST_F(ToplevelWindowEventHandlerTest, GestureDragCaptureLoss) {
 // Tests that dragging a snapped window to another display updates the window's
 // bounds correctly.
 TEST_F(ToplevelWindowEventHandlerTest, DragSnappedWindowToExternalDisplay) {
-  if (!SupportsMultipleDisplays())
-    return;
-
   UpdateDisplay("940x550,940x550");
   int64_t primary_id = display::Screen::GetScreen()->GetPrimaryDisplay().id();
   int64_t secondary_id = display_manager()->GetSecondaryDisplay().id();