Linux: add option to use system harfbuzz.

build/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.
 
 # IMPORTANT:
 # Please don't directly include this file if you are building via gyp_chromium,
 # since gyp_chromium is automatically forcing its inclusion.
 {
   # Variables expected to be overriden on the GYP command line (-D) or by
   # ~/.gyp/include.gypi.
@@ skipping 1123 matching lines @@
         'p2p_apis%' : 0,
 
         # TODO(jrg): when 'gtest_target_type'=='shared_library' and
         # OS==android, make all gtest_targets depend on
         # testing/android/native_test.gyp:native_test_apk.
         'gtest_target_type%': 'shared_library',
 
         # Uses system APIs for decoding audio and video.
         'use_libffmpeg%': '0',
 
-        # Always use the chromium skia. The use_system_harfbuzz needs to
-        # match use_system_skia.
+        # Always use the chromium skia.
         'use_system_skia%': '0',
-        'use_system_harfbuzz%': '0',
 
         # Configure crash reporting and build options based on release type.
         'conditions': [
           ['buildtype=="Official"', {
             # Only report crash dumps for Official builds.
             'linux_breakpad%': 1,
           }, {
             'linux_breakpad%': 0,
           }],
         ],
@@ skipping 2773 matching lines @@
     # settings in target dicts.  SYMROOT is a special case, because many other
     # Xcode variables depend on it, including variables such as
     # PROJECT_DERIVED_FILE_DIR.  When a source group corresponding to something
     # like PROJECT_DERIVED_FILE_DIR is added to a project, in order for the
     # files to appear (when present) in the UI as actual files and not red
     # red "missing file" proxies, the correct path to PROJECT_DERIVED_FILE_DIR,
     # and therefore SYMROOT, needs to be set at the project level.
     'SYMROOT': '<(DEPTH)/xcodebuild',
   },
 }