Changes views_aura_mus_unittests to create DesktopNativeWidgetAura

ui/views/test/platform_test_helper.h

Index: ui/views/test/platform_test_helper.h
diff --git a/ui/views/test/platform_test_helper.h b/ui/views/test/platform_test_helper.h
index 3950007ea4f77967b6fdb70d113afdc6a0a13dcf..7d4b052ccb7cc27c8d6be379a124a08eb9644689 100644
--- a/ui/views/test/platform_test_helper.h
+++ b/ui/views/test/platform_test_helper.h
@@ -13,6 +13,7 @@
 namespace views {
 
 class ViewsTestHelper;
+class Widget;
 
 class PlatformTestHelper {
  public:
@@ -35,6 +36,9 @@ class PlatformTestHelper {
   // called.
   virtual void OnTestHelperCreated(ViewsTestHelper* helper) {}
 
+  // Simulate an OS-level destruction of the native window held by |widget|.
+  virtual void SimulateNativeDestroy(Widget* widget) = 0;
+
  private:
   DISALLOW_COPY_AND_ASSIGN(PlatformTestHelper);
 };