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

content/common/sandbox_mac_diraccess_unittest.mm

 // 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.
 
 #import <Cocoa/Cocoa.h>
 #include <dirent.h>
 
 extern "C" {
 #include <sandbox.h>
 }
@@ skipping 160 matching lines @@
         std::string(sandbox_dir_cases[i]) + kDeniedSuffix;
     FilePath sibling_sandbox_dir = tmp_dir.Append(
                                       sibling_sandbox_dir_name_denied.c_str());
     ASSERT_TRUE(CreateDirectory(sibling_sandbox_dir));
     ScopedDirectory cleanup_sandbox_sibling(&sibling_sandbox_dir);
 
     EXPECT_TRUE(CheckSandbox(sandbox_dir.value()));
   }
 }
 
-MULTIPROCESS_TEST_MAIN(mac_sandbox_path_access) {
+MULTIPROCESS_TEST_MAIN(mac_sandbox_path_access, NULL) {
   char *sandbox_allowed_dir = getenv(kSandboxAccessPathKey);
   if (!sandbox_allowed_dir)
     return -1;
 
   // Build up a sandbox profile that only allows access to a single directory.
   NSString *sandbox_profile =
       @"(version 1)" \
       "(deny default)" \
       "(allow signal (target self))" \
       "(allow sysctl-read)" \
@@ skipping 107 matching lines @@
     PLOG(ERROR) << "Sandbox breach: was able to write ("
                 << denied_file2.value()
                 << ")";
     return -1;
   }
 
   return 0;
 }
 
 }  // namespace sandbox