Move AlterEnvironment to base/environment.h, implement on Windows.

base/base.gypi

 # 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.
 
 {
   'target_defaults': {
     'variables': {
       'base_target': 0,
     },
     'target_conditions': [
@@ skipping 382 matching lines @@
           'power_monitor/power_monitor_source.cc',
           'power_monitor/power_monitor_source.h',
           'power_monitor/power_observer.h',
           'process/internal_linux.cc',
           'process/internal_linux.h',
           'process/kill.cc',
           'process/kill.h',
           'process/kill_mac.cc',
           'process/kill_posix.cc',
           'process/kill_win.cc',
+          'process/launch.cc',
           'process/launch.h',
           'process/launch_ios.cc',
           'process/launch_mac.cc',
           'process/launch_posix.cc',
           'process/launch_win.cc',
           'process/memory.h',
           'process/memory_linux.cc',
           'process/memory_mac.mm',
           'process/memory_win.cc',
           'process/process.h',
@@ skipping 482 matching lines @@
           ['<(use_system_nspr)==1 and >(nacl_untrusted_build)==0', {
             'sources/': [
               ['exclude', '^third_party/nspr/'],
             ],
           }],
         ],
       }],
     ],
   },
 }