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

ash/mus/window_manager_unittest.cc

Index: ash/mus/window_manager_unittest.cc
diff --git a/ash/mus/window_manager_unittest.cc b/ash/mus/window_manager_unittest.cc
index dfe236b90a374b271f5debcdf8e59e52459fc151..7e29fee549b3e44cfda8517a0e684ab8ffec1ccf 100644
--- a/ash/mus/window_manager_unittest.cc
+++ b/ash/mus/window_manager_unittest.cc
@@ -29,7 +29,8 @@ class WindowTreeClientDelegate : public ui::WindowTreeClientDelegate {
   // ui::WindowTreeClientDelegate:
   void OnEmbed(ui::Window* root) override {}
   void OnDidDestroyClient(ui::WindowTreeClient* client) override {}
-  void OnEventObserved(const ui::Event& event, ui::Window* target) override {}
+  void OnPointerEventObserved(const ui::PointerEvent& event,
+                              ui::Window* target) override {}
 
   DISALLOW_COPY_AND_ASSIGN(WindowTreeClientDelegate);
 };