Buffer cross frame paint timing updates.

chrome/common/BUILD.gn

Index: chrome/common/BUILD.gn
diff --git a/chrome/common/BUILD.gn b/chrome/common/BUILD.gn
index 47d8aff0eaa4d0e2b1bc92936e135c477214bbd8..eafd8cd7faa272bb1fe16d8a758a90f039fa319d 100644
--- a/chrome/common/BUILD.gn
+++ b/chrome/common/BUILD.gn
@@ -113,6 +113,8 @@ static_library("common") {
     "page_load_metrics/page_load_metrics_messages.h",
     "page_load_metrics/page_load_metrics_param_traits.cc",
     "page_load_metrics/page_load_metrics_param_traits.h",
+    "page_load_metrics/page_load_metrics_util.cc",
+    "page_load_metrics/page_load_metrics_util.h",
     "page_load_metrics/page_load_timing.cc",
     "page_load_metrics/page_load_timing.h",
     "page_load_metrics/page_track_decider.cc",
@@ -654,6 +656,8 @@ static_library("test_support") {
   visibility = [ "//chrome/test:*" ]
 
   sources = [
+    "page_load_metrics/test/page_load_metrics_test_util.cc",
+    "page_load_metrics/test/page_load_metrics_test_util.h",
     "search/mock_searchbox.cc",
     "search/mock_searchbox.h",
   ]