GN build fixes, mostly for Mac.

build/config/ios/ios_sdk.py

Index: build/config/ios/ios_sdk.py
diff --git a/build/config/ios/ios_sdk.py b/build/config/ios/ios_sdk.py
new file mode 100644
index 0000000000000000000000000000000000000000..dfec4dbada9d88d80e3fe5167ec1b43a826e2beb
--- /dev/null
+++ b/build/config/ios/ios_sdk.py
@@ -0,0 +1,19 @@
+# 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 subprocess
+import sys
+
+# This script returns the path to the SDK of the given type. Pass the type of
+# SDK you want, which is typically "iphone" or "iphonesimulator".
+#
+# In the GYP build, this is done inside GYP itself based on the SDKROOT
+# variable.
+
+if len(sys.argv) != 2:
+  print "Takes one arg (SDK to find)"
+  sys.exit(1)
+
+print subprocess.check_output(['xcodebuild', '-version', '-sdk',
+                               sys.argv[1], 'Path']).strip()