Make the Windows multi_dll build work in GN

chrome/browser/extensions/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")
 
 assert(enable_extensions)
 
 gypi_values =
     exec_script("//build/gypi_to_gn.py",
                 [ rebase_path("../../chrome_browser_extensions.gypi") ],
                 "scope",
                 [ "../../chrome_browser_extensions.gypi" ])
 
 # GYP version: chrome/chrome_browser_extensions.gypi:browser_extensions
-static_library("extensions") {
+source_set("extensions") {
   sources = []
   sources += rebase_path(gypi_values.chrome_browser_extensions_enabled_sources,
                          ".",
                          "//chrome")
 
   defines = []
 
   # Since browser and browser_extensions actually depend on each other,
   # we must omit the dependency from browser_extensions to browser.
   # However, this means browser_extensions and browser should more or less
@@ skipping 145 matching lines @@
             gypi_values.chrome_browser_extensions_networking_private_sources_winmac,
             ".",
             "//chrome")
   }
 
   if (is_win) {
     deps += [
       "//third_party/iaccessible2",
       "//third_party/isimpledom",
     ]
-  } else if (!is_chromeos) {
+  } else if (use_aura && !is_chromeos) {
     sources += [
       "display_info_provider_aura.cc",
       "display_info_provider_aura.h",
     ]
   }
 
   if (enable_app_list) {
     sources +=
         rebase_path(gypi_values.chrome_browser_extensions_app_list_sources,
                     ".",
                     "//chrome")
   }
 
   if (is_chromeos && use_ozone) {
     sources -= [ "global_shortcut_listener_chromeos.cc" ]
   }
   if (!use_ozone) {
     sources -= [ "global_shortcut_listener_ozone.cc" ]
   }
   if (enable_media_router) {
     defines += [ "ENABLE_MEDIA_ROUTER=1" ]
   }
 }