Skip mulitple-dispay tests on win8

ash/shelf/shelf_widget_unittest.cc

 // Copyright (c) 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ash/shelf/shelf_widget.h"
 
 #include "ash/launcher/launcher.h"
 #include "ash/launcher/launcher_button.h"
 #include "ash/launcher/launcher_model.h"
 #include "ash/launcher/launcher_view.h"
@@ skipping 66 matching lines @@
     TestLauncherAlignment(Shell::GetPrimaryRootWindow(),
                           SHELF_ALIGNMENT_RIGHT,
                           "0,0 352x400");
   }
   {
     SCOPED_TRACE("Single Left");
     TestLauncherAlignment(Shell::GetPrimaryRootWindow(),
                           SHELF_ALIGNMENT_LEFT,
                           "48,0 352x400");
   }
+  if (!SupportsMultipleDisplays())
+    return;
+
   UpdateDisplay("300x300,500x500");
   Shell::RootWindowList root_windows = Shell::GetAllRootWindows();
   {
     SCOPED_TRACE("Primary Bottom");
     TestLauncherAlignment(root_windows[0],
                           SHELF_ALIGNMENT_BOTTOM,
                           "0,0 300x252");
   }
   {
     SCOPED_TRACE("Primary Right");
@@ skipping 48 matching lines @@
   views::Widget* widget = new views::Widget;
   views::Widget::InitParams params(views::Widget::InitParams::TYPE_WINDOW);
   params.bounds = gfx::Rect(0, 0, 200, 200);
   params.context = CurrentContext();
   // Widget is now owned by the parent window.
   widget->Init(params);
   widget->SetFullscreen(true);
 }
 
 }  // namespace ash