Convert startup_metric_utils to use mojo.

components/startup_metric_utils/common/startup_metric_messages.h

Index: components/startup_metric_utils/common/startup_metric_messages.h
diff --git a/components/startup_metric_utils/common/startup_metric_messages.h b/components/startup_metric_utils/common/startup_metric_messages.h
deleted file mode 100644
index a8e454869f16ad693c2d1aa9bc33bc00a69fe619..0000000000000000000000000000000000000000
--- a/components/startup_metric_utils/common/startup_metric_messages.h
+++ /dev/null
@@ -1,13 +0,0 @@
-// 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 <stdint.h>
-
-#include "base/time/time.h"
-#include "ipc/ipc_message_macros.h"
-
-#define IPC_MESSAGE_START StartupMetricMsgStart
-
-IPC_MESSAGE_CONTROL1(StartupMetricHostMsg_RecordRendererMainEntryTime,
-                     base::TimeTicks /* renderer_main_entry_time */)