Make PageLoadMetricsWaiter more resilient

chrome/browser/page_load_metrics/page_load_tracker.h

 // 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.
 
 #ifndef CHROME_BROWSER_PAGE_LOAD_METRICS_PAGE_LOAD_TRACKER_H_
 #define CHROME_BROWSER_PAGE_LOAD_METRICS_PAGE_LOAD_TRACKER_H_
 
 #include <memory>
 #include <vector>
 
@@ skipping 145 matching lines @@
                   PageLoadMetricsEmbedderInterface* embedder_interface,
                   const GURL& currently_committed_url,
                   content::NavigationHandle* navigation_handle,
                   UserInitiatedInfo user_initiated_info,
                   int aborted_chain_size,
                   int aborted_chain_size_same_url);
   ~PageLoadTracker() override;
 
   // PageLoadMetricsUpdateDispatcher::Client implementation:
   void OnTimingChanged() override;
+  void OnSubFrameTimingChanged(const mojom::PageLoadTiming& timing) override;
   void OnMainFrameMetadataChanged() override;
   void OnSubframeMetadataChanged() override;
 
   void Redirect(content::NavigationHandle* navigation_handle);
   void WillProcessNavigationResponse(
       content::NavigationHandle* navigation_handle);
   void Commit(content::NavigationHandle* navigation_handle);
   void DidCommitSameDocumentNavigation(
       content::NavigationHandle* navigation_handle);
   void DidFinishSubFrameNavigation(
@@ skipping 192 matching lines @@
   std::vector<std::unique_ptr<PageLoadMetricsObserver>> observers_;
 
   PageLoadMetricsUpdateDispatcher metrics_update_dispatcher_;
 
   DISALLOW_COPY_AND_ASSIGN(PageLoadTracker);
 };
 
 }  // namespace page_load_metrics
 
 #endif  // CHROME_BROWSER_PAGE_LOAD_METRICS_PAGE_LOAD_TRACKER_H_