Implement large cursors in Mushrome.

ash/mus/bridge/shell_port_mash.cc

Index: ash/mus/bridge/shell_port_mash.cc
diff --git a/ash/mus/bridge/shell_port_mash.cc b/ash/mus/bridge/shell_port_mash.cc
index a01e4bfb50df2571c34f6eda2d388304607a015b..965c70fa6c2ffc2d439b16c5ec106d63d117f0fd 100644
--- a/ash/mus/bridge/shell_port_mash.cc
+++ b/ash/mus/bridge/shell_port_mash.cc
@@ -147,6 +147,10 @@ void ShellPortMash::HideCursor() {
   window_manager_->window_manager_client()->SetCursorVisible(false);
 }
 
+void ShellPortMash::SetCursorSize(ui::CursorSize cursor_size) {
+  window_manager_->window_manager_client()->SetCursorSize(cursor_size);
+}
+
 void ShellPortMash::SetGlobalOverrideCursor(
     base::Optional<ui::CursorData> cursor) {
   window_manager_->window_manager_client()->SetGlobalOverrideCursor(