GTK: Add TRACE_EVENTs around gtk ui events.

chrome/browser/ui/gtk/infobars/infobar_gtk.cc

Index: chrome/browser/ui/gtk/infobars/infobar_gtk.cc
diff --git a/chrome/browser/ui/gtk/infobars/infobar_gtk.cc b/chrome/browser/ui/gtk/infobars/infobar_gtk.cc
index 2c0b31afe07e8348f7cd86c079f14a59e441e3c9..fe15111eac3c3b971ddb033fe607ed798234a340 100644
--- a/chrome/browser/ui/gtk/infobars/infobar_gtk.cc
+++ b/chrome/browser/ui/gtk/infobars/infobar_gtk.cc
@@ -4,6 +4,7 @@
 
 #include "chrome/browser/ui/gtk/infobars/infobar_gtk.h"
 
+#include "base/debug/trace_event.h"
 #include "base/utf_string_conversions.h"
 #include "chrome/browser/infobars/infobar_tab_helper.h"
 #include "chrome/browser/profiles/profile.h"
@@ -212,6 +213,8 @@ void InfoBarGtk::OnCloseButton(GtkWidget* button) {
 
 gboolean InfoBarGtk::OnBackgroundExpose(GtkWidget* sender,
                                         GdkEventExpose* event) {
+  TRACE_EVENT0("ui::gtk", "InfoBarGtk::OnBackgroundExpose");
+
   GtkAllocation allocation;
   gtk_widget_get_allocation(sender, &allocation);
   const int height = allocation.height;