Make GlobalDescriptors::MaybeGet return -1 when the key is not found.

testing/gtest.gyp

 # Copyright (c) 2011 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.
 
 {
   'targets': [
     {
       'target_name': 'gtest',
       'type': 'static_library',
       'sources': [
@@ skipping 55 matching lines @@
         ['os_posix == 1', {
           'defines': [
             # gtest isn't able to figure out when RTTI is disabled for gcc
             # versions older than 4.3.2, and assumes it's enabled.  Our Mac
             # and Linux builds disable RTTI, and cannot guarantee that the
             # compiler will be 4.3.2. or newer.  The Mac, for example, uses
             # 4.2.1 as that is the latest available on that platform.  gtest
             # must be instructed that RTTI is disabled here, and for any
             # direct dependents that might include gtest headers.
             'GTEST_HAS_RTTI=0',
+            'OS_POSIX=1',
           ],
           'direct_dependent_settings': {
             'defines': [
               'GTEST_HAS_RTTI=0',
             ],
           },
         }],
         ['clang==1 or OS=="android"', {
           # We want gtest features that use tr1::tuple, but we currently
           # don't support the variadic templates used by libstdc++'s
@@ skipping 49 matching lines @@
     {
       'target_name': 'gtest_prod',
       'toolsets': ['host', 'target'],
       'type': 'none',
       'sources': [
         'gtest/include/gtest/gtest_prod.h',
       ],
     },
   ],
 }