[PageLoadMetrics] Relax invariants and log the exceptions

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 711eed8760f7c30adc9699d412f778bc571a9d3c..9b37f75a0629d1416d43c1b706e4e3141e04dbc1 100644
--- a/chrome/browser/page_load_metrics/metrics_web_contents_observer.cc
+++ b/chrome/browser/page_load_metrics/metrics_web_contents_observer.cc
@@ -215,7 +215,12 @@ PageLoadTracker* MetricsWebContentsObserver::GetTrackerOrNullForRequest(
     const content::GlobalRequestID& request_id,
     content::ResourceType resource_type,
     base::TimeTicks creation_time) {
-  if (resource_type == content::RESOURCE_TYPE_MAIN_FRAME) {
+  // TODO(jkarlin): The WebContentsTester framework doesn't provide a default
+  // GlobalRequestID to its NavigationHandles. Once the test framework
+  // supports real ids, remove the request_id != content::GlobalRequestID()
+  // condition. See https://crbug.com/711352.
+  if (resource_type == content::RESOURCE_TYPE_MAIN_FRAME &&
+      request_id != content::GlobalRequestID()) {
     // The main frame request can complete either before or after commit, so we
     // look at both provisional loads and the committed load to find a
     // PageLoadTracker with a matching request id. See https://goo.gl/6TzCYN for