WIP: Propagate SurfaceID up window tree hierarchy

services/ui/surfaces/display_compositor_client.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_SURFACES_DISPLAY_COMPOSITOR_CLIENT_
+#define SERVICES_UI_SURFACES_DISPLAY_COMPOSITOR_CLIENT_
+
+namespace ui {
+
+namespace surfaces {
+
+// TODO(fsamuel): In this future, this will be a mojo interface.
+class DisplayCompositorClient {
+ public:
+  virtual void OnSurfaceCreated(const gfx::Size& size,
+                                float device_scale_factor,
+                                const cc::SurfaceId& surface_id) = 0;
+};
+
+}  // namespace surfaces
+
+}  // namespace ui
+
+#endif  // SERVICES_UI_SURFACES_DISPLAY_COMPOSITOR_CLIENT_