Added the Ash.Tab.TimeBetweenSwitchToExistingTabUserActions histogram to track time between tab swit

chrome/chrome_browser_ui.gypi

Index: chrome/chrome_browser_ui.gypi
diff --git a/chrome/chrome_browser_ui.gypi b/chrome/chrome_browser_ui.gypi
index 9509ee2901e880d247ced7eea2132c2cf3bbbec7..c5e795a7bbd6fa5fc254f86165be22bb53f4e4c5 100644
--- a/chrome/chrome_browser_ui.gypi
+++ b/chrome/chrome_browser_ui.gypi
@@ -599,6 +599,8 @@
       'browser/ui/ash/launcher/multi_profile_browser_status_monitor.h',
       'browser/ui/ash/media_delegate_chromeos.cc',
       'browser/ui/ash/media_delegate_chromeos.h',
+      'browser/ui/ash/metrics/user_metrics_recorder_proxy.cc',
+      'browser/ui/ash/metrics/user_metrics_recorder_proxy.h',
       'browser/ui/ash/multi_user/multi_user_context_menu_chromeos.cc',
       'browser/ui/ash/multi_user/multi_user_notification_blocker_chromeos.cc',
       'browser/ui/ash/multi_user/multi_user_notification_blocker_chromeos.h',