Cleanup: supervised_user_theme.cc should not be built if themes are not enabled.

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/crypto.gni")
 import("//build/config/features.gni")
 import("//build/config/ui.gni")
 import("//components/nacl/nacl_defines.gni")
 # //build/config/android/rules.gni imports //tools/grit/grit_rule.gni, which
 # produces a conflict for the "grit" template so we have to only include one.
@@ skipping 605 matching lines @@
   if (enable_app_list) {
     deps += [
       "//ui/app_list",
     ]
   }
   if (enable_managed_users) {
     sources += rebase_path(
         gypi_values.chrome_browser_supervised_user_sources,
         ".", "//chrome")
   }
+  if (enable_managed_users && enable_themes) {
+    sources += rebase_path(
+        gypi_values.chrome_browser_supervised_user_and_themes_sources,
+        ".", "//chrome")
+  }
   if (enable_webrtc) {
     sources += rebase_path(
         gypi_values.chrome_browser_webrtc_sources,
         ".", "//chrome")
   }
   if (enable_service_discovery) {
     sources += rebase_path(
         gypi_values.chrome_browser_service_discovery_sources,
         ".", "//chrome")
   }
@@ skipping 323 matching lines @@
     ]
   }
 
   if (enable_wifi_bootstrapping) {
     sources += [
       "local_discovery/wifi/mock_wifi_manager.cc",
       "local_discovery/wifi/mock_wifi_manager.h",
     ]
   }
 }