Add InitializationStateDcheck, its base class, and their tests

util/misc/initialization_state_dcheck.cc

+// Copyright 2014 The Crashpad Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "util/misc/initialization_state_dcheck.h"
+
+namespace crashpad {
+
+#if DCHECK_IS_ON
+
+InitializationStateDcheck::State InitializationStateDcheck::Begin() {
+  State old_state = state();
+  if (old_state == kStateUninitialized) {
+    set_invalid();
+  }
+
+  return old_state;
+}
+
+#endif
+
+}  // namespace crashpad