Adding Histograms for new Desktop First Run.

tools/metrics/actions/actions.xml

 <!--
 Copyright 2014 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.
 -->
 
 <!--
 This file is a comprehensive list of Chrome user actions along with the owner
 and description for each user action.
 
@@ skipping 14081 matching lines @@
   <description>
     Recorded when showing sign in entry in the sign in promo.
   </description>
 </action>
 
 <action name="Signin_Impression_FromStartPage">
   <owner>gogerald@chromium.org</owner>
   <description>
     Recorded when showing sign in entry in the first run experience.
   </description>
-  <obsolete>Removed from codebase.</obsolete>
 </action>
 
 <action name="Signin_Impression_FromTabSwitcher">
   <owner>bzanotti@chromium.org</owner>
   <description>
     Recorded when showing sign in entry in the tab switcher.
   </description>
 </action>
 
 <action name="Signin_MoreButton_Shown">
@@ skipping 1775 matching lines @@
 <action name="webapps.AddShortcut.Manifest">
   <owner>mlamouri@chromium.org</owner>
   <description>
     Shortcut added to the homescreen with a valid Manifest. This action will be
     recorded in addition to AppShortcut, AppShortcutApple and Bookmark actions
     to keep a trend of whether the webapp also add meta tags.
   </description>
 </action>
 
 </actions>