Correct iOS GN hermetic support.

build/toolchain/mac/linker_driver.py

 #!/usr/bin/env python
 
 # Copyright 2016 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 os
 import os.path
 import shutil
 import subprocess
@@ skipping 34 matching lines @@
   the main compiler driver and the linker driver, then invokes all the
   required tools.
 
   Args:
     args: list of string, Arguments to the script.
   """
 
   if len(args) < 2:
     raise RuntimeError("Usage: linker_driver.py [linker-invocation]")
 
+  for i in xrange(len(args)):
+    if args[i] != '--developer_dir':
+      continue
+    os.environ['DEVELOPER_DIR'] = args[i + 1]
+    del args[i:i+2]
+    break
+
   # Collect arguments to the linker driver (this script) and remove them from
   # the arguments being passed to the compiler driver.
   linker_driver_actions = {}
   compiler_driver_args = []
   for arg in args[1:]:
     if arg.startswith(_LINKER_DRIVER_ARG_PREFIX):
       # Convert driver actions into a map of name => lambda to invoke.
       driver_action = ProcessLinkerDriverArg(arg)
       assert driver_action[0] not in linker_driver_actions
       linker_driver_actions[driver_action[0]] = driver_action[1]
@@ skipping 149 matching lines @@
 _LINKER_DRIVER_ACTIONS = [
     ('dsym,', RunDsymUtil),
     ('unstripped,', RunSaveUnstripped),
     ('strip,', RunStrip),
 ]
 
 
 if __name__ == '__main__':
   Main(sys.argv)
   sys.exit(0)