[Page Load Metrics] PageLoadMetrics Mojofication.

chrome/renderer/page_load_metrics/page_timing_sender.h

+// Copyright 2017 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 CHROME_RENDERER_PAGE_LOAD_METRICS_PAGE_TIMING_SENDER_H_
+#define CHROME_RENDERER_PAGE_LOAD_METRICS_PAGE_TIMING_SENDER_H_
+
+#include "chrome/common/page_load_metrics/page_load_timing.h"
+
+namespace page_load_metrics {
+
+// PageTimingSender is an interface that is responsible for sending page load
+// timing. SendTiming() should be implemented to send page load timing over
+// mojo IPC.
+class PageTimingSender {

[Zhen Wang, 2017/04/19 18:49:54]

Why do we need this interface?

SendTiming can be just a function in PageTimingMetricsSender. Or you can just do
it in PageTimingMetricsSender::SendNow().

This is related to the above comment about MetricsRenderFrameObserver does not
need to do the actual sending.

+ public:
+  virtual void SendTiming(const PageLoadTiming& timing,
+                          const PageLoadMetadata& metadata) = 0;
+};
+
+}  // namespace page_load_metrics
+
+#endif  // CHROME_RENDERER_PAGE_LOAD_METRICS_PAGE_TIMING_SENDER_H_