Use precompiled headers for most large projects.

net/net.gyp

 # Copyright (c) 2011 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.
 
 {
   'variables': {
     'chromium_code': 1,
 
     'linux_link_kerberos%': 0,
     'conditions': [
       ['chromeos==1', {
         # Disable Kerberos on ChromeOS, at least for now.
         # It needs configuration (krb5.conf and so on).
         'use_kerberos%': 0,
       }, {  # chromeos == 0
         'use_kerberos%': 1,
       }],
     ],
   },
+  'includes': [
+    '../build/win_precompile.gypi',
+  ],
   'targets': [
     {
       'target_name': 'net',
       'type': '<(component)',
       'dependencies': [
         '../base/base.gyp:base',
         '../base/base.gyp:base_i18n',
         '../base/third_party/dynamic_annotations/dynamic_annotations.gyp:dynamic_annotations',
         '../build/temp_gyp/googleurl.gyp:googleurl',
         '../crypto/crypto.gyp:crypto',
@@ skipping 1521 matching lines @@
             'tools/dump_cache/url_to_filename_encoder.cc',
             'tools/dump_cache/url_to_filename_encoder.h',
             'tools/dump_cache/url_utilities.h',
             'tools/dump_cache/url_utilities.cc',
           ],
         },
       ],
     }],
   ],
 }