[PageLoadMetrics] Keep track of Ad Sizes on Pages

chrome/browser/page_load_metrics/page_load_metrics_initialize.cc

Index: chrome/browser/page_load_metrics/page_load_metrics_initialize.cc
diff --git a/chrome/browser/page_load_metrics/page_load_metrics_initialize.cc b/chrome/browser/page_load_metrics/page_load_metrics_initialize.cc
index 1eef544c32764859079ef18e1e4c487bda4ae1d2..5180a133882cf84edb103b2d3476efddb161f363 100644
--- a/chrome/browser/page_load_metrics/page_load_metrics_initialize.cc
+++ b/chrome/browser/page_load_metrics/page_load_metrics_initialize.cc
@@ -11,6 +11,7 @@
 #include "chrome/browser/page_load_metrics/observers/android_page_load_metrics_observer.h"
 #endif  // OS_ANDROID
 #include "chrome/browser/page_load_metrics/observers/aborts_page_load_metrics_observer.h"
+#include "chrome/browser/page_load_metrics/observers/ads_page_load_metrics_observer.h"
 #include "chrome/browser/page_load_metrics/observers/amp_page_load_metrics_observer.h"
 #include "chrome/browser/page_load_metrics/observers/core_page_load_metrics_observer.h"
 #include "chrome/browser/page_load_metrics/observers/css_scanning_page_load_metrics_observer.h"
@@ -93,6 +94,7 @@ void PageLoadMetricsEmbedder::RegisterObservers(
     tracker->AddObserver(base::MakeUnique<CssScanningMetricsObserver>());
     tracker->AddObserver(base::MakeUnique<ProtocolPageLoadMetricsObserver>());
     tracker->AddObserver(base::MakeUnique<TabRestorePageLoadMetricsObserver>());
+    tracker->AddObserver(base::MakeUnique<AdsPageLoadMetricsObserver>());
 
     std::unique_ptr<page_load_metrics::PageLoadMetricsObserver> ukm_observer =
         UkmPageLoadMetricsObserver::CreateIfNeeded(web_contents_);