Revert "[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 19e9a9f30ad8ff88ebe75e454f8aa84f98c9b11b..093a74a4beea8b68448b552e4cd228a74724bc02 100644
--- a/chrome/browser/page_load_metrics/page_load_metrics_initialize.cc
+++ b/chrome/browser/page_load_metrics/page_load_metrics_initialize.cc
@@ -11,7 +11,6 @@
 #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"
@@ -95,10 +94,6 @@ void PageLoadMetricsEmbedder::RegisterObservers(
     tracker->AddObserver(base::MakeUnique<CssScanningMetricsObserver>());
     tracker->AddObserver(base::MakeUnique<ProtocolPageLoadMetricsObserver>());
     tracker->AddObserver(base::MakeUnique<TabRestorePageLoadMetricsObserver>());
-    std::unique_ptr<AdsPageLoadMetricsObserver> ads_observer =
-        AdsPageLoadMetricsObserver::CreateIfNeeded();
-    if (ads_observer)
-      tracker->AddObserver(std::move(ads_observer));
 
     std::unique_ptr<page_load_metrics::PageLoadMetricsObserver> ukm_observer =
         UkmPageLoadMetricsObserver::CreateIfNeeded(web_contents_);