exo: Implement notification surface support

components/exo/display.cc

Index: components/exo/display.cc
diff --git a/components/exo/display.cc b/components/exo/display.cc
index 72eb656bb96f8db5b3b5a0988e4bf80f183cd87a..8e43007f69a96e6c767453725a894598f8800c5e 100644
--- a/components/exo/display.cc
+++ b/components/exo/display.cc
@@ -12,6 +12,7 @@
 #include "base/memory/ptr_util.h"
 #include "base/trace_event/trace_event.h"
 #include "base/trace_event/trace_event_argument.h"
+#include "components/exo/notification_surface.h"
 #include "components/exo/shared_memory.h"
 #include "components/exo/shell_surface.h"
 #include "components/exo/sub_surface.h"
@@ -185,4 +186,13 @@ std::unique_ptr<SubSurface> Display::CreateSubSurface(Surface* surface,
   return base::WrapUnique(new SubSurface(surface, parent));
 }
 
+std::unique_ptr<NotificationSurface> Display::CreateNotificationSurface(
+    Surface* surface,
+    const std::string& notification_id) {
+  TRACE_EVENT2("exo", "Display::CreateNotificationSurface", "surface",
+               surface->AsTracedValue(), "notification_id", notification_id);
+
+  return base::WrapUnique(new NotificationSurface(surface, notification_id));
+}
+
 }  // namespace exo