mus: Add watcher for all touch events.

ui/views/mus/window_manager_connection.h

Index: ui/views/mus/window_manager_connection.h
diff --git a/ui/views/mus/window_manager_connection.h b/ui/views/mus/window_manager_connection.h
index fe5869c1207b2c3fb4391cb36968555fc82e5e8c..bb41b9ef19268c41b94211bc93b49bdb729407fb 100644
--- a/ui/views/mus/window_manager_connection.h
+++ b/ui/views/mus/window_manager_connection.h
@@ -28,6 +28,7 @@ namespace views {
 class ClipboardMus;
 class NativeWidget;
 class PointerWatcher;
+class TouchEventWatcher;
 class ScreenMus;
 namespace internal {
 class NativeWidgetDelegate;
@@ -67,6 +68,9 @@ class VIEWS_MUS_EXPORT WindowManagerConnection
   void AddPointerWatcher(PointerWatcher* watcher);
   void RemovePointerWatcher(PointerWatcher* watcher);
 
+  void AddTouchEventWatcher(TouchEventWatcher* watcher);
+  void RemoveTouchEventWatcher(TouchEventWatcher* watcher);
+
  private:
   friend class WindowManagerConnectionTest;
 
@@ -75,6 +79,7 @@ class VIEWS_MUS_EXPORT WindowManagerConnection
 
   // Returns true if there is one or more pointer watchers for this client.
   bool HasPointerWatcher();
+  bool HasTouchEventWatcher();
 
   // ui::WindowTreeClientDelegate:
   void OnEmbed(ui::Window* root) override;
@@ -91,6 +96,9 @@ class VIEWS_MUS_EXPORT WindowManagerConnection
   std::unique_ptr<ui::WindowTreeClient> client_;
   // Must be empty on destruction.
   base::ObserverList<PointerWatcher, true> pointer_watchers_;
+  base::ObserverList<TouchEventWatcher, true> touch_event_watchers_;
+  uint32_t pointer_watcher_observer_id_ = 0u;
+  uint32_t touch_event_watcher_observer_id_ = 0u;
 
   DISALLOW_COPY_AND_ASSIGN(WindowManagerConnection);
 };