PPAPI/NaCl: Make a gyp flag for including the untrusted IPC proxy.

ppapi/ppapi.gyp

 # Copyright (c) 2010 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 is the "public" ppapi.gyp file, which must have dependencies on the
 # redistributable portions of PPAPI only. This prevents circular dependencies
 # in the .gyp files (since ppapi_internal depends on parts of Chrome).
 
 {
+  'conditions': [
+    ['disable_nacl==0 and build_ppapi_ipc_proxy_untrusted==1', {
+      'includes': ['ppapi_proxy_untrusted.gypi'],
+    }],
+  ],
   'variables': {
     'chromium_code': 1,  # Use higher warning level.
   },
   'target_defaults': {
     'conditions': [
       # Linux shared libraries should always be built -fPIC.
       #
       # TODO(ajwong): For internal pepper plugins, which are statically linked
       # into chrome, do we want to build w/o -fPIC?  If so, how can we express
       # that in the build system?
       ['os_posix == 1 and OS != "mac"', {
         'cflags': ['-fPIC', '-fvisibility=hidden'],
 
         # This is needed to make the Linux shlib build happy. Without this,
         # -fvisibility=hidden gets stripped by the exclusion in common.gypi
         # that is triggered when a shared library build is specified.
         'cflags/': [['include', '^-fvisibility=hidden$']],
       }],
     ],
   },
   'includes': [
     'ppapi_sources.gypi',
     'ppapi_cpp.gypi',
     'ppapi_gl.gypi',
   ],
 }