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

chrome/browser/page_load_metrics/page_load_metrics_observer.cc

 // Copyright 2015 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/page_load_metrics_observer.h"
 
+#include "content/public/browser/navigation_handle.h"
+
 namespace page_load_metrics {
 
 PageLoadExtraInfo::PageLoadExtraInfo(
     const base::Optional<base::TimeDelta>& first_background_time,
     const base::Optional<base::TimeDelta>& first_foreground_time,
     bool started_in_foreground,
     bool user_gesture,
     const GURL& committed_url,
     const GURL& start_url,
     const base::Optional<base::TimeDelta>& time_to_commit,
@@ skipping 20 matching lines @@
 PageLoadExtraInfo::PageLoadExtraInfo(const PageLoadExtraInfo& other) = default;
 
 PageLoadExtraInfo::~PageLoadExtraInfo() {}
 
 FailedProvisionalLoadInfo::FailedProvisionalLoadInfo(base::TimeDelta interval,
                                                      net::Error error)
     : time_to_failed_provisional_load(interval), error(error) {}
 
 FailedProvisionalLoadInfo::~FailedProvisionalLoadInfo() {}
 
+TrackingPolicy PageLoadMetricsObserver::ShouldTrackLoad(
+    content::NavigationHandle* navigation_handle) {
+  return navigation_handle->GetURL().SchemeIsHTTPOrHTTPS() ? TRACK : IGNORE;
+}
+
 }  // namespace page_load_metrics