Buffer cross frame paint timing updates.

chrome/browser/page_load_metrics/page_load_metrics_initialize.cc

Index: chrome/browser/page_load_metrics/page_load_metrics_initialize.cc
diff --git a/chrome/browser/page_load_metrics/page_load_metrics_initialize.cc b/chrome/browser/page_load_metrics/page_load_metrics_initialize.cc
index 5b9d15cd189b2a26c44e462b9e9f85a65a74cab7..eb943c334a9842f3bd0807e57952aad969192611 100644
--- a/chrome/browser/page_load_metrics/page_load_metrics_initialize.cc
+++ b/chrome/browser/page_load_metrics/page_load_metrics_initialize.cc
@@ -55,6 +55,7 @@ class PageLoadMetricsEmbedder
   // page_load_metrics::PageLoadMetricsEmbedderInterface:
   bool IsNewTabPageUrl(const GURL& url) override;
   void RegisterObservers(page_load_metrics::PageLoadTracker* tracker) override;
+  std::unique_ptr<base::Timer> CreateTimer() override;
 
  private:
   bool IsPrerendering() const;
@@ -142,6 +143,10 @@ bool PageLoadMetricsEmbedder::IsPrerendering() const {
          nullptr;
 }
 
+std::unique_ptr<base::Timer> PageLoadMetricsEmbedder::CreateTimer() {
+  return base::MakeUnique<base::OneShotTimer>();
+}
+
 bool PageLoadMetricsEmbedder::IsNewTabPageUrl(const GURL& url) {
   Profile* profile =
       Profile::FromBrowserContext(web_contents_->GetBrowserContext());