mus: Embedder can request and observe BeginFrame for embedded client.

services/ui/ws/window_tree.h

 // Copyright 2014 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_WS_WINDOW_TREE_H_
 #define SERVICES_UI_WS_WINDOW_TREE_H_
 
 #include <stdint.h>
 
 #include <map>
@@ skipping 421 matching lines @@
       override;
   void SetCapture(uint32_t change_id, Id window_id) override;
   void ReleaseCapture(uint32_t change_id, Id window_id) override;
   void StartPointerWatcher(bool want_moves) override;
   void StopPointerWatcher() override;
   void SetWindowBounds(
       uint32_t change_id,
       Id window_id,
       const gfx::Rect& bounds,
       const base::Optional<cc::LocalSurfaceId>& local_surface_id) override;
+  void RequestBeginFrames(Id window_id,
+                          cc::mojom::FrameSinkObserverPtr observer) override;
   void SetWindowVisibility(uint32_t change_id,
                            Id window_id,
                            bool visible) override;
   void SetWindowProperty(
       uint32_t change_id,
       Id transport_window_id,
       const std::string& name,
       const base::Optional<std::vector<uint8_t>>& value) override;
   void SetWindowOpacity(uint32_t change_id,
                         Id window_id,
@@ skipping 193 matching lines @@
   // a image move. All weak ptrs are invalidated when a drag is completed.
   base::WeakPtrFactory<WindowTree> drag_weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(WindowTree);
 };
 
 }  // namespace ws
 }  // namespace ui
 
 #endif  // SERVICES_UI_WS_WINDOW_TREE_H_