mus: Add PointerWatcher for passively observing mouse and touch events

ash/mus/shell_delegate_mus.cc

Index: ash/mus/shell_delegate_mus.cc
diff --git a/ash/mus/shell_delegate_mus.cc b/ash/mus/shell_delegate_mus.cc
index 8aa0d332dff216baed317a920f1255d8113a37c3..d46d6f5039a414159c761500700cba6a58dbb9d4 100644
--- a/ash/mus/shell_delegate_mus.cc
+++ b/ash/mus/shell_delegate_mus.cc
@@ -9,9 +9,11 @@
 #include "ash/gpu_support_stub.h"
 #include "ash/media_delegate.h"
 #include "ash/mus/context_menu_mus.h"
+#include "ash/mus/pointer_watcher_delegate_mus.h"
 #include "ash/mus/shelf_delegate_mus.h"
 #include "ash/session/session_state_delegate.h"
 #include "ash/system/tray/default_system_tray_delegate.h"
+#include "base/memory/ptr_util.h"
 #include "base/strings/string16.h"
 #include "components/user_manager/user_info_impl.h"
 #include "ui/app_list/presenter/app_list_presenter.h"
@@ -225,6 +227,11 @@ MediaDelegate* ShellDelegateMus::CreateMediaDelegate() {
   return new MediaDelegateStub;
 }
 
+std::unique_ptr<PointerWatcherDelegate>
+ShellDelegateMus::CreatePointerWatcherDelegate() {
+  return base::WrapUnique(new PointerWatcherDelegateMus);
+}
+
 ui::MenuModel* ShellDelegateMus::CreateContextMenu(ash::Shelf* shelf,
                                                    const ShelfItem* item) {
   return new ContextMenuMus(shelf);