ui/base/ime: Fix the cros chrome-sdk build.

This change removes unused X11 includes, which fixes the
ui/base:ui_base_unittests target on the cros chrome-sdk shell build.

R=yhanada@chromium.org

Bug: 867013
Test: none
Change-Id: I42f1d1e72f9cbe35ca585764db19353e8721bfbc
Reviewed-on: https://chromium-review.googlesource.com/1150507Reviewed-by: Yuichiro Hanada <yhanada@chromium.org>
Commit-Queue: James Hawkins <jhawkins@chromium.org>
Cr-Commit-Position: refs/heads/master@{#578290}

ui/base/ime/input_method_chromeos_unittest.cc

@@ -27,9 +27,7 @@
 #include "ui/events/event_utils.h"
 #include "ui/events/keycodes/dom/dom_code.h"
 #include "ui/events/keycodes/dom/keycode_converter.h"
-#include "ui/events/test/events_test_utils_x11.h"
 #include "ui/gfx/geometry/rect.h"
-#include "ui/gfx/x/x11.h"
 
 using base::UTF8ToUTF16;
 using base::UTF16ToUTF8;