Skip test that requires multiple displays on win8

ash/wm/workspace/workspace_layout_manager_unittest.cc

Index: ash/wm/workspace/workspace_layout_manager_unittest.cc
diff --git a/ash/wm/workspace/workspace_layout_manager_unittest.cc b/ash/wm/workspace/workspace_layout_manager_unittest.cc
index 00d965f85ec18d0b06384459a915420da1fc0a18..6194f1c75d5cc89d544ab314654a1e1de59e0473 100644
--- a/ash/wm/workspace/workspace_layout_manager_unittest.cc
+++ b/ash/wm/workspace/workspace_layout_manager_unittest.cc
@@ -92,6 +92,9 @@ TEST_F(WorkspaceLayoutManagerTest, RestoreFromMinimizeKeepsRestore) {
 }
 
 TEST_F(WorkspaceLayoutManagerTest, KeepMinimumVisibilityInDisplays) {
+  if (!SupportsMultipleDisplays())
+    return;
+
   UpdateDisplay("300x400,400x500");
   Shell::RootWindowList root_windows = Shell::GetAllRootWindows();