mus: Implement Window Server Capture

components/mus/public/cpp/window_observer.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 COMPONENTS_MUS_PUBLIC_CPP_WINDOW_OBSERVER_H_
 #define COMPONENTS_MUS_PUBLIC_CPP_WINDOW_OBSERVER_H_
 
 #include <stdint.h>
 
 #include <vector>
@@ skipping 36 matching lines @@
 
   virtual void OnWindowDestroying(Window* window) {}
   virtual void OnWindowDestroyed(Window* window) {}
 
   virtual void OnWindowBoundsChanging(Window* window,
                                       const gfx::Rect& old_bounds,
                                       const gfx::Rect& new_bounds) {}
   virtual void OnWindowBoundsChanged(Window* window,
                                      const gfx::Rect& old_bounds,
                                      const gfx::Rect& new_bounds) {}
+  virtual void OnWindowLostCapture(Window* window) {}
   virtual void OnWindowClientAreaChanged(
       Window* window,
       const gfx::Insets& old_client_area,
       const std::vector<gfx::Rect>& old_additional_client_areas) {}
 
   virtual void OnWindowViewportMetricsChanged(
       Window* window,
       const mojom::ViewportMetrics& old_metrics,
       const mojom::ViewportMetrics& new_metrics) {}
 
@@ skipping 35 matching lines @@
   // allows the close it should destroy the window as appropriate.
   virtual void OnRequestClose(Window* window) {}
 
  protected:
   virtual ~WindowObserver() {}
 };
 
 }  // namespace mus
 
 #endif  // COMPONENTS_MUS_PUBLIC_CPP_WINDOW_OBSERVER_H_