Enable more tests in GN build.

ui/message_center/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/features.gni")
 import("//build/config/ui.gni")
 
 component("message_center") {
   defines = [ "MESSAGE_CENTER_IMPLEMENTATION" ]
 
@@ skipping 144 matching lines @@
   deps = [
     ":message_center",
     "//base",
     "//base/test:test_support",
     "//skia",
     "//ui/gfx",
     "//ui/gfx/geometry",
   ]
 }
 
-# TODO(GYP) Enable this when media is linked.
-if (false) {
-
 test("message_center_unittests") {
   sources = [
     "test/run_all_unittests.cc",
   ]
 
   deps = [
     ":message_center",
     ":test_support",
     "//base",
     "//base/allocator",
@@ skipping 38 matching lines @@
       deps += [
         # Compositor is needed by message_center_view_unittest.cc and for the
         # fonts used by bounded_label_unittest.cc.
         "//ui/compositor",
         "//ui/views",
         "//ui/views:test_support",
       ]
     }
   }  # enable_notifications
 }
-
-}  # if false