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

build/toolchain/mac/BUILD.gn

 # Copyright (c) 2013 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.
 
 # TODO(brettw) Use "gcc_toolchain.gni" like the Linux toolchains. This requires
 # some enhancements since the commands on Mac are slightly different than on
 # Linux.
 
 import("../goma.gni")
 import("//build/config/ios/ios_sdk.gni")
+import("//build/config/mac/mac_sdk.gni")
 
 assert(host_os == "mac")
 
 import("//build/toolchain/goma.gni")
 import("//build/toolchain/toolchain.gni")
 
 if (use_goma) {
   goma_prefix = "$goma_dir/gomacc "
 } else {
   goma_prefix = ""
@@ skipping 204 matching lines @@
     # See //build/toolchain/toolchain.gni for details.
     tool("stamp") {
       command = stamp_command
       description = stamp_description
     }
     tool("copy") {
       command = copy_command
       description = copy_description
     }
 
+    tool("copy_bundle_data") {
+      command = "rm -rf {{output}} && " +
+                "./gyp-mac-tool copy-bundle-resource {{source}} {{output}} True"
+      description = "COPY_BUNDLE_DATA {{source}} {{output}}"
+    }
+    tool("compile_xcassets") {
+      if (is_ios) {
+        _configuration = "Release"
+        if (is_debug) {
+          _configuration = "Debug"
+        }
+
+        _compile_xcassets_env =
+            "IPHONEOS_DEPLOYMENT_TARGET=$ios_deployment_target " +
+            "CONFIGURATION=$ios_sdk_name-$_configuration " +
+            "CONTENTS_FOLDER_PATH=\$(dirname {{output}})"
+      } else {
+        _compile_xcassets_env =
+            "MACOSX_DEPLOYMENT_TARGET=$mac_deployment_target " +
+            "UNLOCALIZED_RESOURCES_FOLDER_PATH=\$(dirname {{output}})"
+      }
+
+      command = "rm -f {{output}} && " +
+                "env $_compile_xcassets_env ./gyp-mac-tool compile-xcassets " +
+                "{} {{inputs}}"
+      description = "COMPILE_XCASSETS {{output}}"
+    }
+
     toolchain_args() {
       current_cpu = invoker.toolchain_cpu
       current_os = invoker.toolchain_os
 
       # These values need to be passed through unchanged.
       host_toolchain = host_toolchain
       target_os = target_os
       target_cpu = target_cpu
 
       if (defined(invoker.is_clang)) {
@@ skipping 50 matching lines @@
 }
 
 mac_toolchain("x64") {
   toolchain_cpu = "x64"
   toolchain_os = "mac"
   cc = "${goma_prefix}/gcc"
   cxx = "${goma_prefix}/g++"
   ld = cxx
   is_clang = false
 }