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

chrome/browser/page_load_metrics/metrics_web_contents_observer.cc

Index: chrome/browser/page_load_metrics/metrics_web_contents_observer.cc
diff --git a/chrome/browser/page_load_metrics/metrics_web_contents_observer.cc b/chrome/browser/page_load_metrics/metrics_web_contents_observer.cc
index 96a71632343470ca0059f38857c9a1e8586a256c..402f1d0e6930dcfb4dae902e3d9fe6c3ed814589 100644
--- a/chrome/browser/page_load_metrics/metrics_web_contents_observer.cc
+++ b/chrome/browser/page_load_metrics/metrics_web_contents_observer.cc
@@ -303,6 +303,8 @@ PageLoadTracker::PageLoadTracker(
       embedder_interface_(embedder_interface) {
   DCHECK(!navigation_handle->HasCommitted());
   embedder_interface_->RegisterObservers(this);
+
+  FilterObservers(navigation_handle);
   for (const auto& observer : observers_) {
     observer->OnStart(navigation_handle, currently_committed_url,
                       started_in_foreground_);
@@ -394,6 +396,18 @@ void PageLoadTracker::LogAbortChainHistograms(
   }
 }
 
+void PageLoadTracker::FilterObservers(
+    content::NavigationHandle* navigation_handle) {
+  auto it = observers_.begin();
+  while (it != observers_.end()) {
+    if ((*it)->ShouldTrackLoad(navigation_handle) == IGNORE) {
+      it = observers_.erase(it);
+    } else {
+      ++it;
+    }
+  }
+}
+
 void PageLoadTracker::WebContentsHidden() {
   // Only log the first time we background in a given page load.
   if (background_time_.is_null()) {
@@ -433,6 +447,8 @@ void PageLoadTracker::Commit(content::NavigationHandle* navigation_handle) {
   // Some transitions (like CLIENT_REDIRECT) are only known at commit time.
   page_transition_ = navigation_handle->GetPageTransition();
   user_gesture_ = navigation_handle->HasUserGesture();
+
+  FilterObservers(navigation_handle);
   for (const auto& observer : observers_) {
     observer->OnCommit(navigation_handle);
   }
@@ -1049,11 +1065,6 @@ void MetricsWebContentsObserver::OnTimingUpdated(
     error = true;
   }
 
-  if (!web_contents()->GetLastCommittedURL().SchemeIsHTTPOrHTTPS()) {
-    RecordInternalError(ERR_IPC_FROM_BAD_URL_SCHEME);
-    error = true;
-  }
-
   if (error)
     return;