Revert "Add precompiled headers to GN build for large targets."

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")
 import("//testing/test.gni")
 
 component("message_center") {
   deps = [
     "//base",
     "//base:i18n",
     "//base/third_party/dynamic_annotations",
     "//skia",
     "//ui/accessibility",
     "//ui/base",
     "//ui/events",
     "//ui/gfx",
     "//ui/gfx/geometry",
     "//ui/native_theme",
     "//ui/resources",
     "//ui/strings",
     "//url",
   ]
 
-  configs += [
-    "//build/config:precompiled_headers",
-
-    # TODO(jschuh): crbug.com/167187 fix size_t to int truncations.
-    "//build/config/compiler:no_size_t_to_int_warning",
-  ]
+  # TODO(jschuh): crbug.com/167187 fix size_t to int truncations.
+  configs += [ "//build/config/compiler:no_size_t_to_int_warning" ]
 
   defines = [ "MESSAGE_CENTER_IMPLEMENTATION" ]
 
   if (enable_notifications && !is_android) {
     sources = [
       "cocoa/notification_controller.h",
       "cocoa/notification_controller.mm",
       "cocoa/opaque_views.h",
       "cocoa/opaque_views.mm",
       "cocoa/popup_collection.h",
@@ skipping 193 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 && !is_android
 }