Skip mulitple-dispay tests on win8

ash/keyboard_overlay/keyboard_overlay_delegate_unittest.cc

Index: ash/keyboard_overlay/keyboard_overlay_delegate_unittest.cc
diff --git a/ash/keyboard_overlay/keyboard_overlay_delegate_unittest.cc b/ash/keyboard_overlay/keyboard_overlay_delegate_unittest.cc
index d7058f6cccbb4b2b9b80bbbcbdaa3d213108331f..0f7158a009aeddffafbc9af2d15c897ed2a747cb 100644
--- a/ash/keyboard_overlay/keyboard_overlay_delegate_unittest.cc
+++ b/ash/keyboard_overlay/keyboard_overlay_delegate_unittest.cc
@@ -18,6 +18,9 @@ typedef test::AshTestBase KeyboardOverlayDelegateTest;
 
 // Verifies we can show and close the widget for the overlay dialog.
 TEST_F(KeyboardOverlayDelegateTest, ShowAndClose) {
+  if (!SupportsMultipleDisplays())
+    return;
+
   UpdateDisplay("500x400,300x200");
   KeyboardOverlayDelegate delegate(ASCIIToUTF16("Title"),
                                    GURL("chrome://keyboardoverlay/"));