Make PageLoadMetricsWaiter more resilient

chrome/browser/page_load_metrics/page_load_metrics_update_dispatcher.h

 // Copyright 2017 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_METRICS_UPDATE_DISPATCHER_H_
 #define CHROME_BROWSER_PAGE_LOAD_METRICS_PAGE_LOAD_METRICS_UPDATE_DISPATCHER_H_
 
 #include <map>
 
 #include "base/macros.h"
@@ skipping 63 matching lines @@
 // stabilized.
 class PageLoadMetricsUpdateDispatcher {
  public:
   // The Client class is updated when metrics managed by the dispatcher have
   // changed. Typically it owns the dispatcher.
   class Client {
    public:
     virtual ~Client() {}
 
     virtual void OnTimingChanged() = 0;
+    virtual void OnSubFrameTimingChanged(
+        const mojom::PageLoadTiming& timing) = 0;
     virtual void OnMainFrameMetadataChanged() = 0;
     virtual void OnSubframeMetadataChanged() = 0;
   };
 
   // The |client| instance must outlive this object.
   PageLoadMetricsUpdateDispatcher(
       Client* client,
       content::NavigationHandle* navigation_handle,
       PageLoadMetricsEmbedderInterface* embedder_interface);
   ~PageLoadMetricsUpdateDispatcher();
@@ skipping 60 matching lines @@
   // Navigation start offsets for the most recently committed document in each
   // frame.
   std::map<FrameTreeNodeId, base::TimeDelta> subframe_navigation_start_offset_;
 
   DISALLOW_COPY_AND_ASSIGN(PageLoadMetricsUpdateDispatcher);
 };
 
 }  // namespace page_load_metrics
 
 #endif  // CHROME_BROWSER_PAGE_LOAD_METRICS_PAGE_LOAD_METRICS_UPDATE_DISPATCHER_H_