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

media/audio/cross_process_notification_unittest.cc

 // 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.
 
 #include "base/compiler_specific.h"
 #include "base/logging.h"
 #include "base/shared_memory.h"
 #include "base/stl_util.h"
 #include "base/test/multiprocess_test.h"
 #include "base/threading/platform_thread.h"
@@ skipping 376 matching lines @@
 struct CrudeIpc {
   uint8 ready;
   CrossProcessNotification::IPCHandle handle_1;
   CrossProcessNotification::IPCHandle handle_2;
 };
 }  // end namespace
 
 // The main routine of the child process.  Waits for the parent process
 // to copy handles over to the child and then uses a CrossProcessNotification to
 // wait and signal to the parent process.
-MULTIPROCESS_TEST_MAIN(CrossProcessNotificationChildMain) {
+MULTIPROCESS_TEST_MAIN(CrossProcessNotificationChildMain, NULL) {
   base::SharedMemory mem;
   bool ok = mem.CreateNamed(
       CrossProcessNotificationMultiProcessTest::kSharedMemName,
       true,
       CrossProcessNotificationMultiProcessTest::kSharedMemSize);
   DCHECK(ok);
   if (!ok) {
     LOG(ERROR) << "Failed to open shared memory segment.";
     return -1;
   }
@@ skipping 48 matching lines @@
 
   ipc->ready = true;
 
   a.Signal();
   a.Wait();
 
   int exit_code = -1;
   base::WaitForExitCode(process, &exit_code);
   EXPECT_EQ(0, exit_code);
 }