Use bundle_data and create_bundle to add support for iOS app bundle.

BUILD.gn

 # Copyright 2014 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.
 
 import("//third_party/icu/config.gni")
 
 if (is_android) {
   import("//build/config/android/rules.gni")
 }
 
@@ skipping 539 matching lines @@
       sources = [ "$root_out_dir/icudtl.dat" ]
       deps = [ ":icudata" ]
       disable_compression = true
     }
   }
 }
 
 # TODO(GYP) support use_system_icu.
 if (icu_use_data_file) {
   if (is_ios) {
-    group("icudata") {
-      # TODO(GYP): Provide an empty group so that this target does not
-      # unconditionally fail. The dat file needs to be bundled separately. In
-      # the longer term, need to figure out how to use system ICU
+    bundle_data("icudata") {
+      sources = [ "source/data/in/icudtl.dat" ]
+      outputs = [ "{{bundle_resources_dir}}/{{source_file_part}}" ]
     }
   } else {
     copy("icudata") {
       if (is_android) {
         sources = [
           "android/icudtl.dat",
         ]
       } else {
         sources = [
           "source/data/in/icudtl.dat",
@@ skipping 42 matching lines @@
         sources = [
           "android/icudtl_dat.S",
         ]
       } else {
         assert(false, "No icu data for this platform")
       }
       defines = [ "U_HIDE_DATA_SYMBOL" ]
     }
   }
 }