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

chrome/chrome_browser_ui.gypi

 # Copyright 2012 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 {
   'variables': {
     # There are two sections of sources:
     # * "Platform"-based sources (OS, toolkit, etc.)
     # * Feature/directory-based sources (e.g., history, printing)
 
@@ skipping 581 matching lines @@
       'browser/ui/ash/launcher/launcher_favicon_loader.cc',
       'browser/ui/ash/launcher/launcher_favicon_loader.h',
       'browser/ui/ash/launcher/launcher_item_controller.cc',
       'browser/ui/ash/launcher/launcher_item_controller.h',
       'browser/ui/ash/launcher/multi_profile_app_window_launcher_controller.cc',
       'browser/ui/ash/launcher/multi_profile_app_window_launcher_controller.h',
       'browser/ui/ash/launcher/multi_profile_browser_status_monitor.cc',
       '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',
       'browser/ui/ash/multi_user/multi_user_util.cc',
       'browser/ui/ash/multi_user/multi_user_util.h',
       'browser/ui/ash/multi_user/multi_user_warning_dialog.cc',
       'browser/ui/ash/multi_user/multi_user_warning_dialog.h',
       'browser/ui/ash/multi_user/multi_user_window_manager.cc',
       'browser/ui/ash/multi_user/multi_user_window_manager.h',
       'browser/ui/ash/multi_user/multi_user_window_manager_chromeos.cc',
@@ skipping 2583 matching lines @@
           ],
           'sources': [
             '<@(chrome_browser_ui_non_mobile_sources)',
             '<@(chrome_browser_ui_omnibox_non_mobile_sources)',
           ],
         }],
       ],
     },
   ],
 }