Add another set of UMA histograms for tab switching on Android.

tools/metrics/histograms/histograms.xml

 <!--
 Copyright 2013 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 used to generate a comprehensive list of Chrome histograms along
 with a detailed description for each histogram.
 
@@ skipping 6599 matching lines @@
 </histogram>
 
 <histogram name="Sqlite.Thumbnail.Error" enum="SqliteErrorCode">
   <summary>Error codes returned by sqlite for the thumbnail db.</summary>
 </histogram>
 
 <histogram name="Sqlite.Web.Error" enum="SqliteErrorCode">
   <summary>Error codes returned by sqlite the web db.</summary>
 </histogram>
 
+<histogram name="Tab.RestoreResult" enum="BooleanSuccess">
+  <summary>
+    When the browser restores a tab, whether the load was successful. Loads can
+    fail for instance when there is no connectivity.
+  </summary>
+</histogram>
+
+<histogram name="Tab.RestoreTime" units="ms">
+  <summary>Load time for a successful tab restore.</summary>
+</histogram>
+
+<histogram name="Tab.RestoreUserPersistence" enum="TabRestoreUserAction">
+  <summary>
+    When the browser restores a tab, whether the user waits for completion of
+    the load or if the user gives up by switching to another tab or leaving
+    Chrome.
+  </summary>
+</histogram>
+
 <histogram name="Tab.SwitchedToForegroundAge" units="ms">
   <summary>Age (in ms) when the tab was switched to foreground.</summary>
 </histogram>
 
 <histogram name="Tab.SwitchedToForegroundLaunchedWithURL"
     enum="TabSwitchedToForegroundLaunchedWithURL">
   <summary>
     Each time a tab is brought to the foreground, this histogram indicates if
     chrome was launched without an URL (i.e., from the launcher), or with an URL
     (i.e., from another app).
@@ skipping 3703 matching lines @@
   <int value="20" label="SQLITE_IOERR_SHMLOCK">Unused</int>
 </enum>
 
 <enum name="SuspendStatus" type="int">
   <int value="0" label="Success"/>
   <int value="1" label="Failure"/>
   <int value="2" label="Cancelled"/>
   <int value="3" label="Attempted"/>
 </enum>
 
+<enum name="TabRestoreUserAction" type="int">
+  <int value="0" label="Wait for completion"/>
+  <int value="1" label="Leave tab (close tab/switch tab/go to tab switcher)"/>
+  <int value="2" label="Leave Chrome"/>
+</enum>
+
 <enum name="TabSwitchedToForegroundLaunchedWithURL" type="int">
   <int value="0" label="Launched without an URL"/>
   <int value="1" label="Launched with an URL"/>
 </enum>
 
 <enum name="TabSwitchedToForegroundRevisit" type="int">
   <int value="0" label="First time"/>
   <int value="1" label="Revisit"/>
 </enum>
 
@@ skipping 1341 matching lines @@
 <fieldtrial name="SSLResumption">
   <group name="Resume_Handshake" label="Session Resumption"/>
   <group name="Full_Handshake" label="Full"/>
   <affected-histogram name="Net.SSL_Connection_Latency"/>
   <affected-histogram name="Net.SSL_Connection_Latency_Google"/>
 </fieldtrial>
 
 </fieldtrials>
 
 </histogram-configuration>