Revert of Remove CAPS

chrome/tools/crash_service/caps/process_singleton_win.cc

+// Copyright 2015 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 <windows.h>
+
+#include "chrome/tools/crash_service/caps/process_singleton_win.h"
+
+namespace caps {
+
+ProcessSingleton::ProcessSingleton() : mutex_(nullptr) {
+  auto mutex = ::CreateMutex(nullptr, TRUE, L"CHROME.CAPS.V1");
+  if (!mutex)
+    return;
+  if (::GetLastError() == ERROR_ALREADY_EXISTS) {
+    ::CloseHandle(mutex);
+    return;
+  }
+  // We are now the single instance.
+  mutex_ = mutex;
+}
+
+ProcessSingleton::~ProcessSingleton() {
+  if (mutex_)
+    ::CloseHandle(mutex_);
+}
+
+}  // namespace caps
+