Add UMA histograms for home page, start page, and DSE hosts.

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 3860 matching lines @@
 </histogram>
 
 <histogram name="HistoryPage.RemoveEntryPosition">
   <summary>
     Number of entries that the deleted entry is older than in History page. Last
     bucket is any entry of that value or higher. Confirmed removal is not
     guaranteed, just an initiation of 'Remove selected items'.
   </summary>
 </histogram>
 
+<histogram name="HomePage.IsHomeButtonEnabled" enum="BooleanEnabled">

[Mark P, 2013/07/26 23:30:23]

You do not use either this histogram or the one below in your code.  Please
remove them.

[bbudge, 2013/07/27 01:33:01]

Leftover from a previous version where I based off another patch. Done.

+  <summary>
+    Whether or not the Home button is enabled in user preferences when a profile
+    is loaded.
+  </summary>
+</histogram>
+
+<histogram name="HomePage.IsNewTabPage" enum="Boolean">
+  <summary>
+    Whether or not the home page user preference is set to the default NTP value
+    when a profile is loaded.
+  </summary>
+</histogram>
+
 <histogram name="HttpCache.EntryLockWait" units="milliseconds">
   <summary>
     The time spent waiting for write lock on a disk cache entry.
   </summary>
 </histogram>
 
 <histogram name="HttpCache.OfflineStatus" enum="OfflineStatus">
   <summary>
     Result of a main page HttpCacheTransaction if offline mode had been enabled.
   </summary>
@@ skipping 8832 matching lines @@
   </summary>
 </histogram>
 
 <histogram name="Search.DefaultSearchProvider" enum="OmniboxSearchEngine">
   <summary>
     The id of the default search engine that is loaded after Chrome startup. See
     src/chrome/browser/search_engines/prepopulate_engines.json for more info.
   </summary>
 </histogram>
 
+<histogram name="Settings.DefaultSearchProvider" enum="OmniboxSearchEngine">
+  <summary>
+    The id of the default search engine URL host that is specified in

[Mark P, 2013/07/26 23:30:23]

Please describe when this is emitted.

(ditto other histograms below)

[bbudge, 2013/07/27 01:33:01]

Done.

+    Preferences.
+  </summary>
+</histogram>
+
+<histogram name="Settings.FirstStartPageURL" enum="OmniboxSearchEngine">
+  <summary>
+    The id of the first start page URL host that is specified in Preferences.

[Mark P, 2013/07/26 23:30:23]

Please revise this comment; it no longer matches the code.

[bbudge, 2013/07/27 01:33:01]

Done.

+    The first start page is the active tab at startup.
+  </summary>
+</histogram>
+
 <histogram name="Settings.HomePageIsNewTabPage" enum="Boolean">
   <summary>
     Whether or not the home page user preference is set to the default NTP value
     when a profile is loaded.
   </summary>
 </histogram>
 
+<histogram name="Settings.HomePageURL" enum="OmniboxSearchEngine">
+  <summary>
+    The id of the home page URL host that is specified in Preferences.
+  </summary>
+</histogram>
+
 <histogram name="Settings.ShowHomeButton" enum="BooleanEnabled">
   <summary>
     Whether or not the Home button is enabled in user preferences when a profile
     is loaded.
   </summary>
 </histogram>
 
 <histogram name="SimpleCache.CheckCRCResult" enum="CheckCRCResult">
   <summary>
     Whether or not the CRC was checked at the moment when the last reference to
@@ skipping 6742 matching lines @@
   <int value="77" label="SAPO"/>
   <int value="82" label="UOL Busca"/>
   <int value="83" label="@MAIL.RU"/>
   <int value="85" label="Zoznam"/>
   <int value="87" label="Najdi.si"/>
   <int value="89" label="AltaVista"/>
   <int value="90" label="Terra"/>
   <int value="99" label="Spray"/>
   <int value="100" label="Sanook!"/>
   <int value="101" label="MYNET"/>
+  <int value="102" label="searchnu.com"/>
+  <int value="103" label="babylon.com"/>
+  <int value="104" label="delta-search.com"/>
+  <int value="105" label="iminent.com"/>
+  <int value="106" label="hao123.com"/>
+  <int value="107" label="sweetim.com"/>
+  <int value="108" label="snap.do"/>
+  <int value="109" label="snapdo.com"/>
+  <int value="110" label="softonic.com"/>
+  <int value="111" label="searchfunmoods.com"/>
+  <int value="112" label="incredibar.com"/>
+  <int value="113" label="sweetpacks.com"/>
+  <int value="114" label="imesh.net"/>
 </enum>
 
 <enum name="OmniboxSuggestRequests" type="int">
   <int value="1" label="requests sent"/>
   <int value="2" label="requests invalidated"/>
   <int value="3" label="(non-invalidated) replies received"/>
 </enum>
 
 <enum name="OSAgnosticErrno" type="int">
   <summary>Errno values with the same meanings on Mac/Win/Linux.</summary>
@@ skipping 4053 matching lines @@
   <group name="Disabled" label="Neither extra webstore link is visible"/>
   <group name="FooterLink" label="Link in bottom right of footer"/>
   <group name="PlusIcon" label="Plus icon in apps page"/>
   <affected-histogram name="Extensions.AppLaunch"/>
   <affected-histogram name="NewTabPage.DefaultPageType"/>
 </fieldtrial>
 
 </fieldtrials>
 
 </histogram-configuration>