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 12712 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 provider that is specified in user

[Mark P, 2013/07/30 15:32:56]

This is not the id of the default search engine provider.  It's the id of the
domain of the default search engine provider.  There's a substantial difference
(some percent of our users, for instance, have a google domain as their default
search provider but not the pre-populated google ID search engine).

[bbudge, 2013/07/30 18:47:08]

Fixed the comment.

+    preferences when a profile is loaded.
+  </summary>
+</histogram>
+
+<histogram name="Settings.HomePageDomain" enum="OmniboxSearchEngine">
+  <summary>
+    The id of the home page domain that is specified in user preferences when a
+    profile is loaded.
+  </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.ShowHomeButton" enum="BooleanEnabled">
   <summary>
     Whether or not the Home button is enabled in user preferences when a profile
     is loaded.
   </summary>
 </histogram>
 
+<histogram name="Settings.StartPageDomains" enum="OmniboxSearchEngine">
+  <summary>
+    The ids of all start page domains that are specified 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
     a read-only entry stream is closed.
   </summary>
 </histogram>
 
 <histogram name="SimpleCache.CreationToIndex" units="milliseconds">
   <summary>
     The time from the creation of the simple cache backend until the index has
@@ skipping 6704 matching lines @@
   <int value="24" label="Pogodak!"/>
   <int value="25" label="Seznam"/>
   <int value="26" label="Centrum"/>
   <int value="27" label="Atlas"/>
   <int value="28" label="Jubii"/>
   <int value="29" label="Eniro"/>
   <int value="30" label="NetSprint"/>
   <int value="32" label="diri"/>
   <int value="33" label="Custom"/>
   <int value="35" label="AOL"/>
+  <int value="36" label="Conduit"/>
   <int value="37" label="Rediff"/>
   <int value="38" label="guruji"/>
   <int value="40" label="GO.com"/>
   <int value="41" label="Rednano"/>
   <int value="44" label="NETI"/>
   <int value="45" label="DELFI"/>
   <int value="46" label="Fonecta 02.fi"/>
+  <int value="50" label="AVG"/>
   <int value="51" label="search.ch"/>
   <int value="54" label="in.gr"/>
   <int value="55" label="Walla!"/>
   <int value="59" label="leit.is"/>
   <int value="62" label="Virgilio"/>
   <int value="63" label="Libero"/>
   <int value="67" label="Naver"/>
   <int value="68" label="Daum"/>
   <int value="69" label="Nate"/>
   <int value="71" label="LATNE"/>
   <int value="72" label="ABC S.k"/>
   <int value="73" label="Kvasir"/>
   <int value="75" label="Onet.pl"/>
   <int value="76" label="Wirtualna Polska"/>
   <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>