Get rid of the use_glib gn variable.

build/config/BUILD.gn

 # Copyright (c) 2013 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/allocator.gni")
 import("//build/config/chrome_build.gni")
 import("//build/config/crypto.gni")
 import("//build/config/features.gni")
 import("//build/config/ui.gni")
 import("//build/module_args/v8.gni")
@@ skipping 97 matching lines @@
   }
   if (use_cairo) {
     defines += [ "USE_CAIRO=1" ]
   }
   if (use_clipboard_aurax11) {
     defines += [ "USE_CLIPBOARD_AURAX11=1" ]
   }
   if (use_default_render_theme) {
     defines += [ "USE_DEFAULT_RENDER_THEME=1" ]
   }
-  if (use_glib) {
-    defines += [ "USE_GLIB=1" ]
-  }
   if (use_openssl) {
     defines += [ "USE_OPENSSL=1" ]
   }
   if (use_openssl_certs) {
     defines += [ "USE_OPENSSL_CERTS=1" ]
   }
   if (use_nss_certs) {
     defines += [ "USE_NSS_CERTS=1" ]
   }
   if (use_ozone) {
@@ skipping 218 matching lines @@
       "CoreFoundation.framework",
       "CoreGraphics.framework",
       "CoreText.framework",
       "Foundation.framework",
       "UIKit.framework",
     ]
   } else if (is_linux) {
     libs = [ "dl" ]
   }
 }