Add missing #include, fix build

TBR=brucedawson

Bug: none
Change-Id: Ief0ae90da4d04abfb66e7ebca89849ed9003570f
Reviewed-on: https://chromium-review.googlesource.com/1063836Reviewed-by: Hans Wennborg <hans@chromium.org>
Reviewed-by: Bruce Dawson <brucedawson@chromium.org>
Cr-Commit-Position: refs/heads/master@{#559475}

ui/events/keycodes/dom/dom_keyboard_layout_manager.h

@@ -6,6 +6,7 @@
 #define UI_EVENTS_KEYCODES_DOM_DOM_KEYBOARD_LAYOUT_MANAGER_H_
 
 #include <map>
+#include <memory>
 #include <vector>
 
 #include "ui/events/keycodes/dom/dom_keyboard_layout.h"