[Cleanup] Move all browsertests to use ScopedFeatureList to modify features

chrome/browser/page_load_metrics/observers/ads_page_load_metrics_observer.cc

Index: chrome/browser/page_load_metrics/observers/ads_page_load_metrics_observer.cc
diff --git a/chrome/browser/page_load_metrics/observers/ads_page_load_metrics_observer.cc b/chrome/browser/page_load_metrics/observers/ads_page_load_metrics_observer.cc
index 49610fdb6f044314ee7054fef983b1af732a5330..63b34f146410253ff92d417ae1eb4bf584706879 100644
--- a/chrome/browser/page_load_metrics/observers/ads_page_load_metrics_observer.cc
+++ b/chrome/browser/page_load_metrics/observers/ads_page_load_metrics_observer.cc
@@ -7,7 +7,6 @@
 #include <string>
 #include <utility>
 
-#include "base/feature_list.h"
 #include "base/logging.h"
 #include "base/memory/ptr_util.h"
 #include "base/strings/string_util.h"
@@ -17,10 +16,14 @@
 #include "content/public/browser/web_contents.h"
 #include "url/gurl.h"
 
-namespace {
+namespace features {
 
 const base::Feature kAdsFeature{"AdsMetrics", base::FEATURE_ENABLED_BY_DEFAULT};
 
+}  // namespace features
+
+namespace {
+
 bool FrameIsAd(content::NavigationHandle* navigation_handle) {
   // Because sub-resource filtering isn't always enabled, and doesn't work
   // well in monitoring mode (no CSS enforcement), it's difficult to identify
@@ -71,7 +74,7 @@ AdsPageLoadMetricsObserver::AdFrameData::AdFrameData(
 // static
 std::unique_ptr<AdsPageLoadMetricsObserver>
 AdsPageLoadMetricsObserver::CreateIfNeeded() {
-  if (!base::FeatureList::IsEnabled(kAdsFeature))
+  if (!base::FeatureList::IsEnabled(features::kAdsFeature))
     return nullptr;
   return base::MakeUnique<AdsPageLoadMetricsObserver>();
 }