Convert startup_metric_utils to use mojo.

components/startup_metric_utils/browser/startup_metric_message_filter.h

-// 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.
-
-#ifndef COMPONENTS_STARTUP_METRIC_UTILS_BROWSER_STARTUP_METRIC_MESSAGE_FILTER_H_
-#define COMPONENTS_STARTUP_METRIC_UTILS_BROWSER_STARTUP_METRIC_MESSAGE_FILTER_H_
-
-#include <stdint.h>
-
-#include "base/macros.h"
-#include "base/time/time.h"
-#include "content/public/browser/browser_message_filter.h"
-
-namespace startup_metric_utils {
-
-class StartupMetricMessageFilter : public content::BrowserMessageFilter {
- public:
-  StartupMetricMessageFilter();
-  bool OnMessageReceived(const IPC::Message& message) override;
-
- private:
-  ~StartupMetricMessageFilter() override = default;
-  void OnRecordRendererMainEntryTime(
-      const base::TimeTicks& renderer_main_entry_time);
-
-  DISALLOW_COPY_AND_ASSIGN(StartupMetricMessageFilter);
-};
-
-}  // namespace startup_metric_utils
-
-#endif  // COMPONENTS_STARTUP_METRIC_UTILS_BROWSER_STARTUP_METRIC_MESSAGE_FILTER_H_