Mus+Ash: propagate Surface ID to parents

services/ui/public/cpp/surface_id_handler.h

+// Copyright 2016 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.
+
+#ifndef SERVICES_UI_PUBLIC_CPP_SURFACE_ID_HANDLER_H_
+#define SERVICES_UI_PUBLIC_CPP_SURFACE_ID_HANDLER_H_
+
+namespace ui {
+
+class SurfaceIdHandler {
+ public:
+  // Called when a child window allocates a new surface ID.
+  // If the handler wishes to retain ownership of the |surface_id|,
+  // and |surface_sequence|, it should return true.
+  virtual bool OnChildWindowSurfaceCreated(
+      Window* window,
+      const cc::SurfaceId& surface_id,
+      const cc::SurfaceSequence& surface_sequence,
+      const gfx::Size& frame_size,
+      float device_scale_factor) = 0;
+};
+
+}  // namespace ui
+
+#endif  // SERVICES_UI_PUBLIC_CPP_SURFACE_ID_HANDLER_H_