Audit GN cflags and defines to match GYP build.

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")
 
 # //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 319 matching lines @@
                            ".",
                            "//chrome")
   }
   if (enable_background) {
     sources += rebase_path(gypi_values.chrome_browser_background_sources,
                            ".",
                            "//chrome")
     if (!use_aura || is_win || is_chromeos) {
       sources -= [ "background/background_mode_manager_aura.cc" ]
     }
-    defines += [ "ENABLE_BACKGROUND=1" ]
   }
   if (enable_task_manager) {
     sources += rebase_path(gypi_values.chrome_browser_task_manager_sources,
                            ".",
                            "//chrome")
   }
   if (enable_spellcheck) {
     sources += rebase_path(gypi_values.chrome_browser_spellchecker_sources,
                            ".",
                            "//chrome")
@@ skipping 748 matching lines @@
     ]
   }
 
   if (enable_wifi_bootstrapping) {
     sources += [
       "local_discovery/wifi/mock_wifi_manager.cc",
       "local_discovery/wifi/mock_wifi_manager.h",
     ]
   }
 }