[iOS/Mac/GN] Update timestamp when copying a tree.

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")
@@ skipping 265 matching lines @@
     }
 
     tool("copy_bundle_data") {
       if (is_ios) {
         _extra_args = "--strings-format=binary1"
       } else {
         _extra_args = ""
       }
       _tool = rebase_path("//build/toolchain/mac/copy_bundle_data.py",
                           root_build_dir)
-      command = "python $_tool ${_extra_args} {{source}} {{output}}"
+      command = "python $_tool --version-for-gn=1 " +
+                "${_extra_args} {{source}} {{output}}"
       description = "COPY_BUNDLE_DATA {{source}} {{output}}"
       pool = ":bundle_pool($default_toolchain)"
     }
     tool("compile_xcassets") {
       _tool = rebase_path("//build/toolchain/mac/compile_xcassets.py",
                           root_build_dir)
       if (is_ios) {
         _sdk_name = ios_sdk_name
         _min_deployment_target = ios_deployment_target
       } else {
         _sdk_name = mac_sdk_name
         _min_deployment_target = mac_deployment_target
       }
-      command = "rm -f {{output}} && " +
-                "python $_tool -p $_sdk_name -t $_min_deployment_target " +
-                "-o {{output}} {{inputs}}"
+      command = "python $_tool --version-for-gn=1 -p $_sdk_name " +
+                "-t $_min_deployment_target -o {{output}} {{inputs}}"
 
       description = "COMPILE_XCASSETS {{output}}"
       pool = ":bundle_pool($default_toolchain)"
     }
 
     toolchain_args() {
       current_cpu = invoker.toolchain_cpu
       current_os = invoker.toolchain_os
 
       # These values need to be passed through unchanged.
@@ skipping 82 matching lines @@
 }
 
 mac_toolchain("x64") {
   toolchain_cpu = "x64"
   toolchain_os = "mac"
   cc = "${goma_prefix}/gcc"
   cxx = "${goma_prefix}/g++"
   ld = cxx
   is_clang = false
 }