Initial addition of Blimp engine crash client code (take 2)

blimp/engine/app/blimp_engine_crash_keys.h

+// Copyright 2016 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.
+
+#ifndef BLIMP_ENGINE_APP_BLIMP_ENGINE_CRASH_KEYS_H_
+#define BLIMP_ENGINE_APP_BLIMP_ENGINE_CRASH_KEYS_H_
+
+#include <stddef.h>
+
+namespace blimp {
+namespace engine {
+
+// Registers the crash keys needed for the Blimp engine. Returns the size of the
+// union of all keys.
+size_t RegisterEngineCrashKeys();
+
+}  // namespace engine
+}  // namespace blimp
+
+#endif  // BLIMP_ENGINE_APP_BLIMP_ENGINE_CRASH_KEYS_H_