Add a new GetInstance() method for singleton classes, take 2.

chrome/browser/zygote_main_linux.cc

 // Copyright (c) 2010 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 <dlfcn.h>
 #include <fcntl.h>
 #include <pthread.h>
 #include <sys/epoll.h>
 #include <sys/prctl.h>
 #include <sys/signal.h>
@@ skipping 364 matching lines @@
           SeccompSandboxSetProcSelfMaps(proc_self_maps);
         }
         close(g_proc_fd);
         g_proc_fd = -1;
       }
 #endif
 
       close(kBrowserDescriptor);  // our socket from the browser
       if (g_suid_sandbox_active)
         close(kZygoteIdDescriptor);  // another socket from the browser
-      Singleton<base::GlobalDescriptors>()->Reset(mapping);
+      base::GlobalDescriptors::GetInstance()->Reset(mapping);
 
 #if defined(CHROMIUM_SELINUX)
       SELinuxTransitionToTypeOrDie("chromium_renderer_t");
 #endif
 
       // Reset the process-wide command line to our new command line.
       CommandLine::Reset();
       CommandLine::Init(0, NULL);
       CommandLine::ForCurrentProcess()->InitFromArgv(args);
       CommandLine::SetProcTitle();
@@ skipping 343 matching lines @@
       VLOG(1) << "Enabling experimental Seccomp sandbox.";
       sandbox_flags |= ZygoteHost::kSandboxSeccomp;
     }
   }
 #endif  // SECCOMP_SANDBOX
 
   Zygote zygote(sandbox_flags);
   // This function call can return multiple times, once per fork().
   return zygote.ProcessRequests();
 }