X11: Add window cache

ui/base/x/BUILD.gn

 # Copyright 2016 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 import("//build/config/ui.gni")
 import("//ui/ozone/ozone.gni")
 
 assert(use_x11 || ozone_platform_x11)
 
 component("x") {
   output_name = "ui_base_x"
@@ skipping 17 matching lines @@
     "//base",
     "//base:i18n",
     "//skia",
     "//ui/events",
     "//ui/events/devices/x11",
     "//ui/events/keycodes:x11",
     "//ui/gfx",
     "//ui/gfx/x",
   ]
 }
+
+component("x_window_cache") {
+  output_name = "ui_base_x_window_cache"
+
+  defines = [ "UI_BASE_X_IMPLEMENTATION" ]
+
+  sources = [
+    "x11_window_cache.cc",
+    "x11_window_cache.h",
+  ]
+
+  configs += [ "//build/config/linux:x11" ]
+
+  deps = [
+    "//base",
+    "//ui/events/platform/x11",
+  ]
+}