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

content/common/sandbox_mac_unittest_helper.mm

 // 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.
 
 #include "content/common/sandbox_mac_unittest_helper.h"
 
 extern "C" {
 #include <sandbox.h>
 }
 
@@ skipping 107 matching lines @@
 
   return it->second;
 }
 
 }  // namespace sandboxtest
 
 namespace {
 
 // Main function for driver process that enables the sandbox and runs test
 // code.
-MULTIPROCESS_TEST_MAIN(mac_sandbox_test_runner) {
+MULTIPROCESS_TEST_MAIN(mac_sandbox_test_runner, NULL) {
   TestContentClient content_client;
   content::SetContentClient(&content_client);
   // Extract parameters.
   char* sandbox_type_str = getenv(kSandboxTypeKey);
   if (!sandbox_type_str) {
     LOG(ERROR) << "Sandbox type not specified";
     return -1;
   }
   content::SandboxType sandbox_type =
       static_cast<content::SandboxType>(atoi(sandbox_type_str));
@@ skipping 30 matching lines @@
 
   if (!test_case->SandboxedTest()) {
     LOG(ERROR) << sandbox_test_name << "Failed sandboxed test";
     return -1;
   }
 
   return 0;
 }
 
 }  // namespace