Add support for counting same-document AMP loads.

chrome/browser/page_load_metrics/page_load_metrics_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/page_load_metrics_observer.h"
 
 #include <utility>
 
 namespace page_load_metrics {
 
@@ skipping 88 matching lines @@
 PageLoadMetricsObserver::ObservePolicy PageLoadMetricsObserver::OnRedirect(
     content::NavigationHandle* navigation_handle) {
   return CONTINUE_OBSERVING;
 }
 
 PageLoadMetricsObserver::ObservePolicy PageLoadMetricsObserver::OnCommit(
     content::NavigationHandle* navigation_handle) {
   return CONTINUE_OBSERVING;
 }
 
-PageLoadMetricsObserver::ObservePolicy
-PageLoadMetricsObserver::OnDidFinishSubFrameNavigation(
-    content::NavigationHandle* navigation_handle) {
-  return CONTINUE_OBSERVING;
-}
-
 PageLoadMetricsObserver::ObservePolicy PageLoadMetricsObserver::OnHidden(
     const PageLoadTiming& timing,
     const PageLoadExtraInfo& extra_info) {
   return CONTINUE_OBSERVING;
 }
 
 PageLoadMetricsObserver::ObservePolicy PageLoadMetricsObserver::OnShown() {
   return CONTINUE_OBSERVING;
 }
 
 PageLoadMetricsObserver::ObservePolicy
 PageLoadMetricsObserver::FlushMetricsOnAppEnterBackground(
     const PageLoadTiming& timing,
     const PageLoadExtraInfo& extra_info) {
   return CONTINUE_OBSERVING;
 }
 
 PageLoadMetricsObserver::ObservePolicy
 PageLoadMetricsObserver::ShouldObserveMimeType(
     const std::string& mime_type) const {
   return mime_type == "text/html" || mime_type == "application/xhtml+xml"
              ? CONTINUE_OBSERVING
              : STOP_OBSERVING;
 }
 
 }  // namespace page_load_metrics