Fix dependency tree when using the system ICU.

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 783 matching lines @@
 
     # Use system nspr instead of the bundled one.
     'use_system_nspr%': 0,
 
     # Use system protobuf instead of bundled one.
     'use_system_protobuf%': 0,
 
     # Use system yasm instead of bundled one.
     'use_system_yasm%': 0,
 
+    # Use system ICU instead of bundled one.
+    'use_system_icu%' : 0,
+
     # Default to enabled PIE; this is important for ASLR but we may need to be
     # able to turn it off for various reasons.
     'linux_disable_pie%': 0,
 
     # The release channel that this build targets. This is used to restrict
     # channel-specific build options, like which installer packages to create.
     # The default is 'all', which does no channel-specific filtering.
     'channel%': 'all',
 
     # Override chromium_mac_pch and set it to 0 to suppress the use of
@@ skipping 3471 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',
   },
 }