Build some x11 dependent files only if 'use_x11'

chrome/browser/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/chrome_build.gni")
 import("//build/config/crypto.gni")
 import("//build/config/features.gni")
 import("//build/config/ui.gni")
 import("//build/split_static_library.gni")
 import("//chrome/common/features.gni")
@@ skipping 3480 matching lines @@
       "renderer_context_menu/spelling_options_submenu_observer.h",
     ]
   }
 
   if (is_desktop_linux) {
     # Desktop linux, doesn't count ChromeOS.
     sources += [
       "first_run/upgrade_util.cc",
       "first_run/upgrade_util_linux.cc",
       "first_run/upgrade_util_linux.h",
-      "fullscreen_aurax11.cc",
       "icon_loader_auralinux.cc",
-      "media/webrtc/window_icon_util_x11.cc",
       "password_manager/native_backend_kwallet_x.cc",
       "password_manager/native_backend_kwallet_x.h",
       "platform_util_linux.cc",
       "shell_integration_linux.cc",
       "shell_integration_linux.h",
       "speech/tts_linux.cc",
-      "themes/theme_service_aurax11.cc",
-      "themes/theme_service_aurax11.h",
       "web_applications/web_app_linux.cc",
     ]
 
+    if (use_x11) {
+      sources += [
+        "fullscreen_aurax11.cc",
+        "media/webrtc/window_icon_util_x11.cc",
+
+        # ThemeServiceAuraX11 does not depend on X11, although its
+        # instantiation/inclusion in theme_service_factory.cc is conditioned
+        # by USE_X11.
+        # TODO(tonikitoo): Check if non-x11 could benefit from it. If so,
+        # rename and use it.
+        "themes/theme_service_aurax11.cc",
+        "themes/theme_service_aurax11.h",
+      ]
+    }
+
     # libsecret hard depends on GLib.
     if (use_glib) {
       sources += [
         "password_manager/native_backend_libsecret.cc",
         "password_manager/native_backend_libsecret.h",
       ]
       defines += [ "USE_LIBSECRET" ]
       deps += [ "//third_party/libsecret" ]
     }
   }
@@ skipping 824 matching lines @@
   # linking all of the test support.
   static_library("pepper_cdm_test_constants") {
     testonly = true
     visibility = [ "//chrome/*" ]
     sources = [
       "media/pepper_cdm_test_constants.cc",
       "media/pepper_cdm_test_constants.h",
     ]
   }
 }