[Page Load Metrics] Add mojom file to page load metrics.

chrome/common/page_load_metrics/page_load_metrics_param_traits.h

+// Copyright (c) 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_COMMON_PAGE_LOAD_METRICS_PAGE_LOAD_METRICS_PARAM_TRAITS_H_
+#define CHROME_COMMON_PAGE_LOAD_METRICS_PAGE_LOAD_METRICS_PARAM_TRAITS_H_
+
+#include "chrome/common/page_load_metrics/page_load_metrics.mojom.h"
+#include "ipc/ipc_message_utils.h"
+
+namespace IPC {
+
+// mojom::PageLoadTiming contains child mojom structs, which are stored in
+// mojo::StructPtr<>s. IPC doesn't have ParamTraits for mojo::StructPtr<>, so we
+// provide custom ParamTraits for PageLoadTiming here. This is temporary while
+// we run a field trial to verify there are no metric regressions due to
+// migrating to mojo, and will be removed once the field trial is complete and
+// shows expected results.
+template <>
+struct ParamTraits<page_load_metrics::mojom::PageLoadTiming> {
+  typedef page_load_metrics::mojom::PageLoadTiming param_type;
+  static void GetSize(base::PickleSizer* s, const param_type& p);
+  static void Write(base::Pickle* m, const param_type& p);
+  static bool Read(const base::Pickle* m,
+                   base::PickleIterator* iter,
+                   param_type* p);
+  static void Log(const param_type& p, std::string* l);
+};
+
+}  // namespace IPC
+
+#endif  // CHROME_COMMON_PAGE_LOAD_METRICS_PAGE_LOAD_METRICS_PARAM_TRAITS_H_