Buffer cross frame paint timing updates.

chrome/browser/page_load_metrics/page_load_tracker.cc

 // Copyright 2016 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/browser/page_load_metrics/page_load_tracker.h"
 
 #include <algorithm>
 #include <ostream>
 #include <string>
 #include <utility>
@@ skipping 180 matching lines @@
 }
 
 PageLoadTracker::~PageLoadTracker() {
   if (app_entered_background_) {
     RecordAppBackgroundPageLoadCompleted(true);
   }
 
   if (did_stop_tracking_)
     return;
 
+  metrics_update_dispatcher_.ShutDown();

[Charlie Harrison, 2017/05/30 14:49:07]

optional: It seems a bit strange to have a Shutdown() method called in the
destructor. What about having the dispatcher just be a unique_ptr and call reset
here?

[Bryan McQuade, 2017/05/30 15:30:23]

It's not that unusual / strange - see
https://cs.chromium.org/search/?q=::~+Shutdown

+
   if (page_end_time_.is_null()) {
     // page_end_time_ can be unset in some cases, such as when a navigation is
     // aborted by a navigation that started before it. In these cases, set the
     // end time to the current time.
     RecordInternalError(ERR_NO_PAGE_LOAD_END_TIME);
     NotifyPageEnd(END_OTHER, UserInitiatedInfo::NotUserInitiated(),
                   base::TimeTicks::Now(), true);
   }
 
   if (!did_commit_) {
@@ skipping 408 matching lines @@
 }
 
 void PageLoadTracker::OnSubframeMetadataChanged() {
   PageLoadExtraInfo extra_info(ComputePageLoadExtraInfo());
   for (const auto& observer : observers_) {
     observer->OnLoadingBehaviorObserved(extra_info);
   }
 }
 
 }  // namespace page_load_metrics