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

ipc/ipc.gyp

 # 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.
 
 {
   'variables': {
     'chromium_code': 1,
   },
   'includes': [
     'ipc.gypi',
@@ skipping 15 matching lines @@
         'include_dirs': [
           '..',
         ],
       },
     },
     {
       'target_name': 'ipc_tests',
       'type': '<(gtest_target_type)',
       'dependencies': [
         'ipc',
+        'test_support_ipc',
         '../base/base.gyp:base',
         '../base/base.gyp:base_i18n',
         '../base/base.gyp:test_support_base',
         '../base/third_party/dynamic_annotations/dynamic_annotations.gyp:dynamic_annotations',
         '../testing/gtest.gyp:gtest',
       ],
       'include_dirs': [
         '..'
       ],
       'sources': [
@@ skipping 30 matching lines @@
           ],
         }]
       ],
     },
     {
       'target_name': 'test_support_ipc',
       'type': 'static_library',
       'dependencies': [
         'ipc',
         '../base/base.gyp:base',
+        '../testing/gtest.gyp:gtest',
       ],
       'sources': [
+        'ipc_multiprocess_test.cc',
+        'ipc_multiprocess_test.h',
         'ipc_test_sink.cc',
         'ipc_test_sink.h',
       ],
     },
   ],
   'conditions': [
     ['OS=="win"', {
       'targets': [
         {
           'target_name': 'ipc_win64',
@@ skipping 35 matching lines @@
           'variables': {
             'test_suite_name': 'ipc_tests',
             'input_shlib_path': '<(SHARED_LIB_DIR)/<(SHARED_LIB_PREFIX)ipc_tests<(SHARED_LIB_SUFFIX)',
             'input_jars_paths': ['<(PRODUCT_DIR)/lib.java/chromium_base.jar',],
           },
           'includes': [ '../build/apk_test.gypi' ],
         }],
     }],
   ],
 }