Disable shadows in notification toasts on Windows classic theme.

ui/message_center/views/notification_view.cc

Index: ui/message_center/views/notification_view.cc
diff --git a/ui/message_center/views/notification_view.cc b/ui/message_center/views/notification_view.cc
index b66de84929a83391df4e6231fc0183f1ba2fed2a..fe91d1b09469a099755b1165664ef94720302697 100644
--- a/ui/message_center/views/notification_view.cc
+++ b/ui/message_center/views/notification_view.cc
@@ -50,6 +50,10 @@
 #include "ui/views/widget/widget.h"
 #include "url/gurl.h"
 
+#if defined(OS_WIN)
+#include "ui/base/win/shell.h"
+#endif
+
 namespace {
 
 // Dimensions.
@@ -198,6 +202,13 @@ NotificationView* NotificationView::Create(MessageCenterController* controller,
     return notification_view;
 #endif
 
+#if defined(OS_WIN)
+  // Don't create shadows for notifications on Windows under classic theme.
+  if (top_level && !ui::win::IsAeroGlassEnabled()) {
+    return notification_view;
+  }
+#endif  // OS_WIN
+
   notification_view->CreateShadowBorder();
   return notification_view;
 }