Get the proper Mac SDK path for the GN build.

build/config/mac/mac_sdk.gni

 # 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.
 
 declare_args() {
   # Minimum supported version of the Mac SDK.
   mac_sdk_min = "10.6"
 
   # Path to a specific version of the Mac SDKJ, not including a backslash at
   # the end. If empty, the path to the lowest version greater than or equal to
   # mac_sdk_min is used.
   mac_sdk_path = ""
 }
 
+find_sdk_args = [ "--print_sdk_path" ]
 if (is_chrome_branded && is_official_build) {
-  find_sdk_args = [ "--verify", mac_sdk_min "--sdk_path=" + mac_sdk_path ]
+  find_sdk_args += [ "--verify", mac_sdk_min "--sdk_path=" + mac_sdk_path ]
 } else {
-  find_sdk_args = [ mac_sdk_min ]
+  find_sdk_args += [ mac_sdk_min ]
 }
-# Use "list lines" and take the first to get version string without a newline.
+# The tool will print the SDK path on the first line, and the version on the
+# second line.
 find_sdk_lines =
     exec_script("//build/mac/find_sdk.py", find_sdk_args, "list lines")
-mac_sdk_version = find_sdk_lines[0]
+mac_sdk_version = find_sdk_lines[1]
 if (mac_sdk_path == "") {
-  mac_sdk_root = "/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX"
-  mac_sdk_path = mac_sdk_root + mac_sdk_version + ".sdk"
+  # TODO(brettw) when everybody moves to XCode 5 we can remove the

[Nico, 2014/01/16 22:52:58]

Add a reference to just-filed http://crbug.com/335325 please

+  # --print_sdk_path argument to find_sdk and instead just use the following
+  # two lines. This saves a process fork.
+  #mac_sdk_root = "/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX"
+  #mac_sdk_path = mac_sdk_root + mac_sdk_version + ".sdk"
+  mac_sdk_path = find_sdk_lines[0]
 }