[page_load_metrics] Add support for chrome:// urls and add extensions observer

chrome/browser/page_load_metrics/page_load_metrics_observer.cc

Index: chrome/browser/page_load_metrics/page_load_metrics_observer.cc
diff --git a/chrome/browser/page_load_metrics/page_load_metrics_observer.cc b/chrome/browser/page_load_metrics/page_load_metrics_observer.cc
index 6ac706be85a0eefabdb90c4347c877fcb0ed8030..6fe1ef20f861ac925faf20b419481b5b100c32ad 100644
--- a/chrome/browser/page_load_metrics/page_load_metrics_observer.cc
+++ b/chrome/browser/page_load_metrics/page_load_metrics_observer.cc
@@ -4,6 +4,8 @@
 
 #include "chrome/browser/page_load_metrics/page_load_metrics_observer.h"
 
+#include "content/public/browser/navigation_handle.h"
+
 namespace page_load_metrics {
 
 PageLoadExtraInfo::PageLoadExtraInfo(
@@ -44,4 +46,9 @@ FailedProvisionalLoadInfo::FailedProvisionalLoadInfo(base::TimeDelta interval,
 
 FailedProvisionalLoadInfo::~FailedProvisionalLoadInfo() {}
 
+TrackingPolicy PageLoadMetricsObserver::ShouldTrackLoad(
+    content::NavigationHandle* navigation_handle) {
+  return navigation_handle->GetURL().SchemeIsHTTPOrHTTPS() ? TRACK : IGNORE;
+}
+
 }  // namespace page_load_metrics