Buffer cross frame paint timing updates.

chrome/browser/page_load_metrics/metrics_web_contents_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/browser/page_load_metrics/metrics_web_contents_observer.h"
 
 #include <algorithm>
 #include <ostream>
 #include <string>
 #include <utility>
@@ skipping 85 matching lines @@
 
   MetricsWebContentsObserver* metrics = FromWebContents(web_contents);
   if (!metrics) {
     metrics = new MetricsWebContentsObserver(web_contents, create_params,
                                              std::move(embedder_interface));
     web_contents->SetUserData(UserDataKey(), base::WrapUnique(metrics));
   }
   return metrics;
 }
 
-MetricsWebContentsObserver::~MetricsWebContentsObserver() {
+MetricsWebContentsObserver::~MetricsWebContentsObserver() {}
+
+void MetricsWebContentsObserver::WebContentsDestroyed() {
   // TODO(csharrison): Use a more user-initiated signal for CLOSE.
   NotifyPageEndAllLoads(END_CLOSE, UserInitiatedInfo::NotUserInitiated());
 
+  // We tear down PageLoadTrackers in WebContentsDestroyed, rather than in the
+  // destructor, since |web_contents()| returns nullptr in the destructor, and
+  // PageLoadMetricsObservers can cause code to execute that wants to be able to
+  // access the current WebContents.
+  committed_load_ = nullptr;
+  provisional_loads_.clear();
+  aborted_provisional_loads_.clear();
+
   for (auto& observer : testing_observers_)
     observer.OnGoingAway();
 }
-

[Charlie Harrison, 2017/05/26 19:31:34]

keep the whitespace

[Bryan McQuade, 2017/05/26 20:07:32]

Done

 void MetricsWebContentsObserver::RegisterInputEventObserver(
     content::RenderViewHost* host) {
   if (host != nullptr)
     host->GetWidget()->AddInputEventObserver(this);
 }
 
 void MetricsWebContentsObserver::UnregisterInputEventObserver(
     content::RenderViewHost* host) {
   if (host != nullptr)
     host->GetWidget()->RemoveInputEventObserver(this);
@@ skipping 560 matching lines @@
     observer_->RemoveTestingObserver(this);
     observer_ = nullptr;
   }
 }
 
 void MetricsWebContentsObserver::TestingObserver::OnGoingAway() {
   observer_ = nullptr;
 }
 
 }  // namespace page_load_metrics