Add support for counting same-document AMP loads.

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 313 matching lines @@
 
   std::unique_ptr<PageLoadTracker> finished_nav(
       std::move(provisional_loads_[navigation_handle]));
   provisional_loads_.erase(navigation_handle);
 
   // Ignore same-document navigations.
   if (navigation_handle->HasCommitted() &&
       navigation_handle->IsSameDocument()) {
     if (finished_nav)
       finished_nav->StopTracking();
+    if (committed_load_)
+      committed_load_->DidCommitSameDocumentNavigation(navigation_handle);
     return;
   }
 
   // Ignore internally generated aborts for navigations with HTTP responses that
   // don't commit, such as HTTP 204 responses and downloads.
   if (!navigation_handle->HasCommitted() &&
       navigation_handle->GetNetErrorCode() == net::ERR_ABORTED &&
       navigation_handle->GetResponseHeaders()) {
     if (finished_nav)
       finished_nav->StopTracking();
@@ skipping 298 matching lines @@
     observer_->RemoveTestingObserver(this);
     observer_ = nullptr;
   }
 }
 
 void MetricsWebContentsObserver::TestingObserver::OnGoingAway() {
   observer_ = nullptr;
 }
 
 }  // namespace page_load_metrics