When a font family pref changes to the empty string, pass it to WebKit.

chrome/chrome_common.gypi

 # Copyright (c) 2012 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.
 
 {
   'targets': [
     {
       'target_name': 'common',
       'type': 'static_library',
       'variables': {
@@ skipping 252 matching lines @@
         'common/nacl_messages.cc',
         'common/nacl_messages.h',
         'common/nacl_types.cc',
         'common/nacl_types.h',
         'common/password_form_fill_data.cc',
         'common/password_form_fill_data.h',
         'common/password_generation_util.cc',
         'common/password_generation_util.h',
         'common/pepper_flash.cc',
         'common/pepper_flash.h',
+        'common/pref_names_util.cc',
+        'common/pref_names_util.h',
         'common/print_messages.cc',
         'common/print_messages.h',
         'common/profiling.cc',
         'common/profiling.h',
         'common/ref_counted_util.h',
         'common/render_messages.cc',
         'common/render_messages.h',
         'common/safe_browsing/safebrowsing_messages.h',
         'common/search_provider.h',
         'common/service_messages.h',
@@ skipping 305 matching lines @@
         'common/metrics/proto/user_action_event.proto',
       ],
       'variables': {
         'proto_in_dir': 'common/metrics/proto',
         'proto_out_dir': 'chrome/common/metrics/proto',
       },
       'includes': [ '../build/protoc.gypi' ],
     },
   ],
 }