Added a system caret used for accessibility on Windows.

ui/accessibility/BUILD.gn

 # Copyright 2014 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/linux/pkg_config.gni")
 import("//build/config/features.gni")
 import("//build/config/ui.gni")
 import("//testing/libfuzzer/fuzzer_test.gni")
 import("//testing/test.gni")
 import("//tools/json_schema_compiler/json_schema_api.gni")
@@ skipping 119 matching lines @@
   }
 
   java_cpp_enum("ax_enumerations_srcjar") {
     sources = [
       "ax_enums.idl",
     ]
   }
 }
 
 static_library("test_support") {
+  testonly = true
   sources = [
     "tree_generator.cc",
     "tree_generator.h",
   ]
 
   if (is_win) {
     sources += [
       "platform/test_ax_node_wrapper.cc",
       "platform/test_ax_node_wrapper.h",
     ]
   }
 
   deps = [
     ":accessibility",
   ]
 }
 
 test("accessibility_unittests") {
+  testonly = true
   sources = [
     "ax_generated_tree_unittest.cc",
     "ax_node_position_unittest.cc",
     "ax_text_utils_unittest.cc",
     "ax_tree_combiner_unittest.cc",
     "ax_tree_serializer_unittest.cc",
     "ax_tree_unittest.cc",
+    "platform/ax_fake_caret_win_interactive_uitest.cc",
     "platform/ax_platform_node_win_unittest.cc",
   ]
 
   deps = [
     ":accessibility",
     ":ax_gen",
     ":test_support",
     "//base",
     "//base/test:run_all_unittests",
     "//skia",
     "//testing/gtest",
     "//ui/base",
     "//ui/gfx",
     "//ui/gfx/geometry",
   ]
 
   if (is_win) {
-    deps += [ "//third_party/iaccessible2" ]
+    deps += [
+      "//third_party/iaccessible2",
+      "//ui/views/:test_support",
+    ]
+    libs = [ "oleacc.lib" ]
   }
 }
 
 json_schema_api("ax_gen") {
   sources = [
     "ax_enums.idl",
   ]
   deps = [
     "//base/third_party/dynamic_annotations",
   ]
   root_namespace = "ui"
   schemas = true
 }
 
 fuzzer_test("ax_tree_fuzzer") {
   sources = [
     "ax_tree_fuzzer.cc",
   ]
 
   deps = [
     ":accessibility",
   ]
 }