Buffer cross frame paint timing updates.

chrome/renderer/page_load_metrics/metrics_render_frame_observer.cc

 // 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 "chrome/renderer/page_load_metrics/metrics_render_frame_observer.h"
 
 #include <string>
 
 #include "base/feature_list.h"
 #include "base/memory/ptr_util.h"
@@ skipping 189 matching lines @@
         base::TimeDelta::FromSecondsD(
             perf.AuthorStyleSheetParseDurationBeforeFCP());
   }
   if (perf.UpdateStyleDurationBeforeFCP() > 0.0) {
     timing->style_sheet_timing->update_style_duration_before_fcp =
         base::TimeDelta::FromSecondsD(perf.UpdateStyleDurationBeforeFCP());
   }
   return timing;
 }
 
-std::unique_ptr<base::Timer> MetricsRenderFrameObserver::CreateTimer() const {
-  return base::WrapUnique(new base::OneShotTimer);
+std::unique_ptr<base::Timer> MetricsRenderFrameObserver::CreateTimer() {
+  return base::MakeUnique<base::OneShotTimer>();
 }
 
 std::unique_ptr<PageTimingSender>
 MetricsRenderFrameObserver::CreatePageTimingSender() {
   if (base::FeatureList::IsEnabled(features::kPageLoadMetricsMojofication)) {
     return base::WrapUnique<PageTimingSender>(
         new MojoIPCPageTimingSender(render_frame()));
   }
   return base::WrapUnique<PageTimingSender>(
       new LegacyIPCPageTimingSender(render_frame(), routing_id()));
 }
 
 bool MetricsRenderFrameObserver::HasNoRenderFrame() const {
   bool no_frame = !render_frame() || !render_frame()->GetWebFrame();
   DCHECK(!no_frame);
   return no_frame;
 }
 
 void MetricsRenderFrameObserver::OnDestruct() {
   delete this;
 }
 
 }  // namespace page_load_metrics