Make SysColorChangeListener Windows-only instead of having an empty shell.

ui/gfx/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/ui.gni")
 import("//testing/test.gni")
 
 if (is_android) {
   import("//build/config/android/config.gni")
   import("//build/config/android/rules.gni")
@@ skipping 313 matching lines @@
   # Windows.
   if (is_win) {
     cflags = [ "/wd4324" ]  # Structure was padded due to __declspec(align()), which is
                             # uninteresting.
   } else {
     sources -= [
       "gdi_util.cc",
       "gdi_util.h",
       "icon_util.cc",
       "icon_util.h",
+      "sys_color_change_listener.cc",
+      "sys_color_change_listener.h",
     ]
   }
 
   # Linux.
   if (is_linux) {
     configs += [ "//build/config/linux:fontconfig" ]
   }
 
   # Chrome OS
   if (is_chromeos) {
@@ skipping 206 matching lines @@
 if (is_android) {
   generate_jni("gfx_jni_headers") {
     sources = [
       "../android/java/src/org/chromium/ui/gfx/BitmapHelper.java",
       "../android/java/src/org/chromium/ui/gfx/DeviceDisplayInfo.java",
       "../android/java/src/org/chromium/ui/gfx/ViewConfigurationHelper.java",
     ]
     jni_package = "gfx"
   }
 }