mus: Change PointerWatcher to observe all pointer events, with moves optional.

services/ui/demo/mus_demo.cc

Index: services/ui/demo/mus_demo.cc
diff --git a/services/ui/demo/mus_demo.cc b/services/ui/demo/mus_demo.cc
index 89b601e034eb74f060cbdab7a9c96437cd90e7cc..cfbf80e14eac0fdc53f4e6fe2b6a92c586fdde4a 100644
--- a/services/ui/demo/mus_demo.cc
+++ b/services/ui/demo/mus_demo.cc
@@ -84,7 +84,8 @@ void MusDemo::OnDidDestroyClient(WindowTreeClient* client) {
   timer_.Stop();
 }
 
-void MusDemo::OnEventObserved(const Event& event, Window* target) {}
+void MusDemo::OnPointerEventObserved(const PointerEvent& event,
+                                     Window* target) {}
 
 void MusDemo::SetWindowManagerClient(WindowManagerClient* client) {}