[Mac/GN] List missing nscolor_additions.mm file in //ui/base.

ui/base/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/buildflag_header.gni")
 import("//build/config/compiler/compiler.gni")
 import("//build/config/sanitizers/sanitizers.gni")
 import("//build/config/ui.gni")
 import("//testing/test.gni")
 import("//ui/base/ui_features.gni")
@@ skipping 97 matching lines @@
     "cocoa/fullscreen_window_manager.h",
     "cocoa/fullscreen_window_manager.mm",
     "cocoa/hover_button.h",
     "cocoa/hover_button.mm",
     "cocoa/hover_image_button.h",
     "cocoa/hover_image_button.mm",
     "cocoa/menu_controller.h",
     "cocoa/menu_controller.mm",
     "cocoa/nib_loading.h",
     "cocoa/nib_loading.mm",
+    "cocoa/nscolor_additions.h",
+    "cocoa/nscolor_additions.mm",
     "cocoa/nsgraphics_context_additions.h",
     "cocoa/nsgraphics_context_additions.mm",
     "cocoa/nsview_additions.h",
     "cocoa/nsview_additions.mm",
     "cocoa/remote_layer_api.h",
     "cocoa/remote_layer_api.mm",
     "cocoa/scoped_cg_context_smooth_fonts.h",
     "cocoa/scoped_cg_context_smooth_fonts.mm",
     "cocoa/three_part_image.h",
     "cocoa/three_part_image.mm",
@@ skipping 637 matching lines @@
       "cocoa/cocoa_base_utils_unittest.mm",
       "cocoa/constrained_window/constrained_window_animation_unittest.mm",
       "cocoa/controls/blue_label_button_unittest.mm",
       "cocoa/controls/hover_image_menu_button_unittest.mm",
       "cocoa/controls/hyperlink_button_cell_unittest.mm",
       "cocoa/controls/hyperlink_text_view_unittest.mm",
       "cocoa/focus_tracker_unittest.mm",
       "cocoa/fullscreen_window_manager_unittest.mm",
       "cocoa/hover_image_button_unittest.mm",
       "cocoa/menu_controller_unittest.mm",
+      "cocoa/nscolor_additions_unittest.mm",
       "cocoa/nsgraphics_context_additions_unittest.mm",
       "cocoa/nsview_additions_unittest.mm",
       "cocoa/three_part_image_unittest.mm",
       "cocoa/tracking_area_unittest.mm",
       "models/list_model_unittest.cc",
       "models/list_selection_model_unittest.cc",
       "models/tree_node_model_unittest.cc",
       "test/data/resource.h",
       "text/bytes_formatting_unittest.cc",
       "touch/selection_bound_unittest.cc",
@@ skipping 169 matching lines @@
 if (is_mac) {
   mac_framework_bundle("ui_unittests_framework") {
     testonly = true
     deps = [
       "//ui/resources:ui_test_pak_bundle_data",
     ]
     info_plist = "test/framework-Info.plist"
     output_name = "ui_unittests Framework"
   }
 }