mus: Implement Window Server Capture

components/mus/ws/event_dispatcher.h

Index: components/mus/ws/event_dispatcher.h
diff --git a/components/mus/ws/event_dispatcher.h b/components/mus/ws/event_dispatcher.h
index bbd2badce05cc8188c60cb9e6f660d5cc5e29568..c5292d35df11c9ed5988a0508f27c496a315d19c 100644
--- a/components/mus/ws/event_dispatcher.h
+++ b/components/mus/ws/event_dispatcher.h
@@ -33,6 +33,10 @@ class EventDispatcher : public ServerWindowObserver {
 
   void set_surface_id(cc::SurfaceId surface_id) { surface_id_ = surface_id; }
 
+  ServerWindow* capture_window() { return capture_window_; }
+  const ServerWindow* capture_window() const { return capture_window_; }
+  void SetCaptureWindow(ServerWindow* capture_window);
+
   void AddAccelerator(uint32_t id, mojom::EventMatcherPtr event_matcher);
   void RemoveAccelerator(uint32_t id);
 
@@ -67,6 +71,10 @@ class EventDispatcher : public ServerWindowObserver {
   void DispatchToPointerTarget(const PointerTarget& target,
                                mojom::EventPtr event);
 
+  // Cancels all implicit capture. This is called when the explicit capture
+  // state changes.
+  void CancelAllPointerEvents();
+
   // Stops sending pointer events to |window|. This does not remove the entry
   // for |window| from |pointer_targets_|, rather it nulls out the window. This
   // way we continue to eat events until the up/cancel is received.
@@ -91,6 +99,7 @@ class EventDispatcher : public ServerWindowObserver {
 
   EventDispatcherDelegate* delegate_;
   ServerWindow* root_;
+  ServerWindow* capture_window_;
 
   cc::SurfaceId surface_id_;