Add support for counting same-document AMP loads.

chrome/browser/page_load_metrics/observers/ads_page_load_metrics_observer.cc

 // 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.
 
 #include "chrome/browser/page_load_metrics/observers/ads_page_load_metrics_observer.h"
 
 #include <string>
 #include <utility>
 
 #include "base/feature_list.h"
@@ skipping 73 matching lines @@
 AdsPageLoadMetricsObserver::OnCommit(
     content::NavigationHandle* navigation_handle) {
   DCHECK(ad_frames_data_.empty());
 
   // The main frame is never considered an ad.
   ad_frames_data_[navigation_handle->GetFrameTreeNodeId()] = nullptr;
   ProcessOngoingNavigationResource(navigation_handle->GetFrameTreeNodeId());
   return CONTINUE_OBSERVING;
 }
 
-page_load_metrics::PageLoadMetricsObserver::ObservePolicy
-AdsPageLoadMetricsObserver::OnDidFinishSubFrameNavigation(
+void AdsPageLoadMetricsObserver::OnDidFinishSubFrameNavigation(
     content::NavigationHandle* navigation_handle) {
   // Determine if the frame is part of an existing ad, the root of a new ad,
   // or a non-ad frame. Once a frame is labled as an ad, it is always
   // considered an ad, even if it navigates to a non-ad page. This function
   // labels all of a page's frames, even those that fail to commit.
   FrameTreeNodeId frame_tree_node_id = navigation_handle->GetFrameTreeNodeId();
   content::RenderFrameHost* parent_frame_host =
       navigation_handle->GetParentFrame();
 
   const auto& id_and_data = ad_frames_data_.find(frame_tree_node_id);
   if (id_and_data != ad_frames_data_.end()) {
     // An existing subframe is navigating again.
     if (id_and_data->second) {
       // The subframe was an ad to begin with, keep tracking it as an ad.
       ProcessOngoingNavigationResource(frame_tree_node_id);
 
       if (frame_tree_node_id == id_and_data->second->frame_tree_node_id) {
         // This is the top-most frame in the ad.
         UMA_HISTOGRAM_BOOLEAN(
             "PageLoad.Clients.Ads.Google.Navigations.AdFrameRenavigatedToAd",
             FrameIsAd(navigation_handle));
       }
-      return CONTINUE_OBSERVING;
+      return;
     }
     // This frame was previously not an ad, process it as usual. If it had
     // any child frames that were ads, those will still be recorded.
     UMA_HISTOGRAM_BOOLEAN(
         "PageLoad.Clients.Ads.Google.Navigations.NonAdFrameRenavigatedToAd",
         FrameIsAd(navigation_handle));
   }
 
   // Determine who the parent frame's ad ancestor is.
   const auto& parent_id_and_data =
       ad_frames_data_.find(parent_frame_host->GetFrameTreeNodeId());
   if (parent_id_and_data == ad_frames_data_.end()) {
     // We don't know who the parent for this frame is. One possibility is that
     // it's a frame from a previous navigation.
     RecordParentExistsForSubFrame(false /* parent_exists */);
 
-    return CONTINUE_OBSERVING;
+    return;
   }
   RecordParentExistsForSubFrame(true /* parent_exists */);
 
   AdFrameData* ad_data = parent_id_and_data->second;
 
   if (!ad_data && FrameIsAd(navigation_handle)) {
     // This frame is not nested within an ad frame but is itself an ad.
     ad_frames_data_storage_.emplace_back(frame_tree_node_id);
     ad_data = &ad_frames_data_storage_.back();
   }
 
   ad_frames_data_[frame_tree_node_id] = ad_data;
 
   ProcessOngoingNavigationResource(frame_tree_node_id);
-  return CONTINUE_OBSERVING;
 }
 
 page_load_metrics::PageLoadMetricsObserver::ObservePolicy
 AdsPageLoadMetricsObserver::FlushMetricsOnAppEnterBackground(
     const page_load_metrics::PageLoadTiming& timing,
     const page_load_metrics::PageLoadExtraInfo& extra_info) {
   // The browser may come back, but there is no guarantee. To be safe, record
   // what we have now and ignore future changes to this navigation.
   if (extra_info.did_commit)
     RecordHistograms();
@@ skipping 139 matching lines @@
 void AdsPageLoadMetricsObserver::ProcessOngoingNavigationResource(
     FrameTreeNodeId frame_tree_node_id) {
   const auto& frame_id_and_request =
       ongoing_navigation_resources_.find(frame_tree_node_id);
   if (frame_id_and_request == ongoing_navigation_resources_.end())
     return;
 
   ProcessLoadedResource(frame_id_and_request->second);
   ongoing_navigation_resources_.erase(frame_id_and_request);
 }