Fix build with system zlib.

chrome/chrome_browser.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': 'browser',
       'type': 'static_library',
@@ skipping 36 matching lines @@
         '../third_party/cld/cld.gyp:cld',
         '../third_party/expat/expat.gyp:expat',
         '../third_party/hunspell/hunspell.gyp:hunspell',
         '../third_party/icu/icu.gyp:icui18n',
         '../third_party/icu/icu.gyp:icuuc',
         '../third_party/leveldatabase/leveldatabase.gyp:leveldatabase',
         '../third_party/libjingle/libjingle.gyp:libjingle',
         '../third_party/libphonenumber/libphonenumber.gyp:libphonenumber',
         '../third_party/libxml/libxml.gyp:libxml',
         '../third_party/npapi/npapi.gyp:npapi',
+        '../third_party/zlib/zlib.gyp:zlib',
         '../ui/base/strings/ui_strings.gyp:ui_strings',
         '../ui/surface/surface.gyp:surface',
         '../ui/ui.gyp:ui',
         '../ui/ui.gyp:ui_resources',
         '../ui/ui.gyp:ui_resources_2x',
         '../ui/ui.gyp:ui_resources_standard',
         '../v8/tools/gyp/v8.gyp:v8',
         '../webkit/support/webkit_support.gyp:appcache',
         '../webkit/support/webkit_support.gyp:blob',
         '../webkit/support/webkit_support.gyp:database',
@@ skipping 5045 matching lines @@
         'browser/metrics/proto/study.proto',
       ],
       'variables': {
         'proto_in_dir': 'browser/metrics/proto',
         'proto_out_dir': 'chrome/browser/metrics/proto',
       },
       'includes': [ '../build/protoc.gypi' ]
     },
   ],
 }