[page_load_metrics] Add a NavigationThrottle for richer abort metrics

components/page_load_metrics/browser/metrics_web_contents_observer.cc

Index: components/page_load_metrics/browser/metrics_web_contents_observer.cc
diff --git a/components/page_load_metrics/browser/metrics_web_contents_observer.cc b/components/page_load_metrics/browser/metrics_web_contents_observer.cc
index 0c586b7c65e6a9842bfa0a0f6fced893633f73f1..890bf00031c47851b7af01cddc265411ef49202a 100644
--- a/components/page_load_metrics/browser/metrics_web_contents_observer.cc
+++ b/components/page_load_metrics/browser/metrics_web_contents_observer.cc
@@ -251,6 +251,7 @@ PageLoadTracker::PageLoadTracker(
       url_(navigation_handle->GetURL()),
       abort_type_(ABORT_NONE),
       started_in_foreground_(in_foreground),
+      page_transition_(navigation_handle->GetPageTransition()),
       aborted_chain_size_(aborted_chain_size),
       aborted_chain_size_same_url_(aborted_chain_size_same_url),
       embedder_interface_(embedder_interface) {
@@ -276,11 +277,14 @@ PageLoadTracker::~PageLoadTracker() {
     PAGE_LOAD_HISTOGRAM(internal::kCommitToCompleteNoTimingIPCs,
                         base::TimeTicks::Now() - commit_time);
   }
-  // Recall that trackers that are given ABORT_UNKNOWN_NAVIGATION have their
-  // chain length added to the next navigation. Take care not to double count
-  // them. Also do not double count committed loads, which call this already.
-  if (commit_time_.is_null() && abort_type_ != ABORT_UNKNOWN_NAVIGATION)
+
+  // Don't include any aborts that resulted in a new navigation, as the chain
+  // length will be included in the aborter PageLoadTracker.
+  if (commit_time_.is_null() && abort_type_ != ABORT_RELOAD &&
+      abort_type_ != ABORT_FORWARD_BACK &&
+      abort_type_ != ABORT_NEW_NAVIGATION) {
     LogAbortChainHistograms(nullptr);
+  }
 
   for (const auto& observer : observers_) {
     if (failed_provisional_load_info_) {
@@ -372,6 +376,8 @@ void PageLoadTracker::Commit(content::NavigationHandle* navigation_handle) {
   commit_time_ = base::TimeTicks::Now();
   ClampBrowserTimestampIfInterProcessTimeTickSkew(&commit_time_);
   url_ = navigation_handle->GetURL();
+  // Some transitions (like CLIENT_REDIRECT) are only known at commit time.
+  page_transition_ = navigation_handle->GetPageTransition();
   for (const auto& observer : observers_) {
     observer->OnCommit(navigation_handle);
   }
@@ -546,7 +552,7 @@ void PageLoadTracker::UpdateAbort(UserAbortType abort_type,
 }
 
 bool PageLoadTracker::IsLikelyProvisionalAbort(
-    base::TimeTicks abort_cause_time) {
+    base::TimeTicks abort_cause_time) const {
   // Note that |abort_cause_time - abort_time| can be negative.
   return abort_type_ == ABORT_OTHER &&
          (abort_cause_time - abort_time_).InMilliseconds() < 100;
@@ -647,7 +653,7 @@ bool MetricsWebContentsObserver::OnMessageReceived(
   return handled;
 }
 
-void MetricsWebContentsObserver::DidStartNavigation(
+void MetricsWebContentsObserver::WillStartNavigationRequest(
     content::NavigationHandle* navigation_handle) {
   if (!navigation_handle->IsInMainFrame())
     return;
@@ -866,17 +872,19 @@ void MetricsWebContentsObserver::NotifyAbortAllLoadsWithTimestamp(
     UserAbortType abort_type,
     base::TimeTicks timestamp,
     bool is_certainly_browser_timestamp) {
-  if (committed_load_)
+  if (committed_load_) {
     committed_load_->NotifyAbort(abort_type, timestamp,
                                  is_certainly_browser_timestamp);
+  }
   for (const auto& kv : provisional_loads_) {
     kv.second->NotifyAbort(abort_type, timestamp,
                            is_certainly_browser_timestamp);
   }
   for (const auto& tracker : aborted_provisional_loads_) {
-    if (tracker->IsLikelyProvisionalAbort(timestamp))
+    if (tracker->IsLikelyProvisionalAbort(timestamp)) {
       tracker->UpdateAbort(abort_type, timestamp,
                            is_certainly_browser_timestamp);
+    }
   }
   aborted_provisional_loads_.clear();
 }
@@ -897,8 +905,11 @@ MetricsWebContentsObserver::NotifyAbortedProvisionalLoadsNewNavigation(
   aborted_provisional_loads_.pop_back();
 
   base::TimeTicks timestamp = new_navigation->NavigationStart();
-  if (last_aborted_load->IsLikelyProvisionalAbort(timestamp))
-    last_aborted_load->UpdateAbort(ABORT_UNKNOWN_NAVIGATION, timestamp, false);
+  if (last_aborted_load->IsLikelyProvisionalAbort(timestamp)) {
+    last_aborted_load->UpdateAbort(
+        AbortTypeForPageTransition(new_navigation->GetPageTransition()),
+        timestamp, false);
+  }
 
   aborted_provisional_loads_.clear();
   return last_aborted_load;