chromeos: Remove AshTestBase::SupportsMultipleDisplays

ash/display/root_window_transformers_unittest.cc

Index: ash/display/root_window_transformers_unittest.cc
diff --git a/ash/display/root_window_transformers_unittest.cc b/ash/display/root_window_transformers_unittest.cc
index eb850a3cb587402d932ae8f3a8c43e1ec90d0218..fdcc28bd1e0c577141d35ed938864b7b939d8d10 100644
--- a/ash/display/root_window_transformers_unittest.cc
+++ b/ash/display/root_window_transformers_unittest.cc
@@ -255,9 +255,6 @@ TEST_F(RootWindowTransformersTest, MAYBE_RotateAndMagnify) {
 }
 
 TEST_F(RootWindowTransformersTest, ScaleAndMagnify) {
-  if (!SupportsMultipleDisplays())
-    return;
-
   TestEventHandler event_handler;
   Shell::GetInstance()->AddPreTargetHandler(&event_handler);
 
@@ -423,8 +420,6 @@ TEST_F(RootWindowTransformersTest, MAYBE_ConvertHostToRootCoords) {
 }
 
 TEST_F(RootWindowTransformersTest, LetterBoxPillarBox) {
-  if (!SupportsMultipleDisplays())
-    return;
   test::MirrorWindowTestApi test_api;
   display_manager()->SetMultiDisplayMode(display::DisplayManager::MIRRORING);
   UpdateDisplay("400x200,500x500");