android envsetup: Stop honoring --target-arch parameter.

build/gyp_chromium

 #!/usr/bin/env python
 
 # Copyright (c) 2012 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.
 
 # This script is wrapper for Chromium that adds some support for how GYP
 # is invoked by Chromium beyond what can be done in the gclient hooks.
 
 import glob
@@ skipping 159 matching lines @@
           home_dot_gyp = None
         else:
           break
 
   if home_dot_gyp:
     include_gypi = os.path.join(home_dot_gyp, "include.gypi")
     if os.path.exists(include_gypi):
       supplemental_files += [include_gypi]
 
   vars_dict = GetGypVarsForGN(supplemental_files)
+  # It's not possible to let set a default value for cpu_arch in GN, so do it
+  # here for now (http://crbug.com/344767).
+  if vars_dict.get('OS') == 'android' and not 'target_arch' in vars_dict:
+    vars_dict['target_arch'] = 'arm'
+
   gn_args = ''
 
   # Note: These are the additional flags passed to various builds by builders
   # on the main waterfall. We'll probably need to add these at some point:
   #   mac_strip_release=1         http://crbug.com/330301
   #   linux_dump_symbols=0        http://crbug.com/330300
   #   host_os=linux  Probably can skip, GN knows the host OS.
   #   order_text_section=<path>   http://crbug.com/330299
   #   chromium_win_pch=0          http://crbug.com/297678
   #   chromium_ios_signing=0      http://crbug.com/330302
@@ skipping 301 matching lines @@
   # rather than a separate runhooks step so that any environment modifications
   # from above are picked up.
   print 'Running build/landmines.py...'
   subprocess.check_call(
       [sys.executable, os.path.join(script_dir, 'landmines.py')])
 
   if vs2013_runtime_dll_dirs:
     CopyVsRuntimeDlls(GetOutputDirectory(), vs2013_runtime_dll_dirs)
 
   sys.exit(gyp_rc)