Convert PageLoadMetrics to Mojo

components/page_load_metrics/common/BUILD.gn

 # 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.
 
+import("//mojo/public/tools/bindings/mojom.gni")
+
 # GYP version: components/page_load_metrics.gypi:page_load_metrics_common
 static_library("common") {
   sources = [
     "page_load_metrics_messages.cc",
     "page_load_metrics_messages.h",
     "page_load_timing.cc",
     "page_load_timing.h",
   ]
   deps = [
     "//base",
     "//ipc",
   ]
 }
+
+mojom("page_load_metrics_mojom") {
+  sources = [
+    "page_load_metrics.mojom",
+  ]
+}