Add metrics for search engine promo and search widget

tools/metrics/histograms/histograms.xml

Index: tools/metrics/histograms/histograms.xml
diff --git a/tools/metrics/histograms/histograms.xml b/tools/metrics/histograms/histograms.xml
index 9c8710c1e12704589b4ab52ca22379fdf2014244..1fd8de745706d6afff6fb108d4f77f7e7a4b80a8 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -65549,6 +65549,114 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="SearchEnginePromo.ExistingDevices.FirstSearchEngineListed"
+    enum="OmniboxSearchEngineType">
+  <owner>yusufo@chromium.org</owner>
+  <summary>
+    The first search engine listed in the options for search engine promo. This
+    is a dialog prompting the user to pick a default search engine. The dialog
+    was shown on a device that had Chrome before it was first introduced.
+  </summary>
+</histogram>
+
+<histogram name="SearchEnginePromo.ExistingDevices.SearchEngineSelection"
+    enum="OmniboxSearchEngineType">
+  <owner>yusufo@chromium.org</owner>
+  <summary>
+    The search engine selected by the user from the search engine promo. This is
+    a dialog prompting the user to pick a default search engine. The dialog was
+    shown on a device that had Chrome before it was first introduced.
+  </summary>
+</histogram>
+
+<histogram name="SearchEnginePromo.ExistingDevices.SecondSearchEngineListed"
+    enum="OmniboxSearchEngineType">
+  <owner>yusufo@chromium.org</owner>
+  <summary>
+    The second search engine listed in the options for search engine promo. This
+    is a dialog prompting the user to pick a default search engine. The dialog
+    was shown on a device that had Chrome before it was first introduced.
+  </summary>
+</histogram>
+
+<histogram name="SearchEnginePromo.ExistingDevices.ThirdSearchEngineListed"
+    enum="OmniboxSearchEngineType">
+  <owner>yusufo@chromium.org</owner>
+  <summary>
+    The third search engine listed in the options for search engine promo. This
+    is a dialog prompting the user to pick a default search engine. The dialog
+    was shown on a device that had Chrome before it was first introduced.
+  </summary>
+</histogram>
+
+<histogram name="SearchEnginePromo.NewDevices.FirstSearchEngineListed"
+    enum="OmniboxSearchEngineType">
+  <owner>yusufo@chromium.org</owner>
+  <summary>
+    The first search engine listed in the options for search engine promo. This
+    is a dialog prompting the user to pick a default search engine. The dialog
+    was shown on a device that used Chrome after it was first introduced.
+  </summary>
+</histogram>
+
+<histogram name="SearchEnginePromo.NewDevices.PartnershipSearchEngineUsed"
+    enum="OmniboxSearchEngineType">
+  <owner>yusufo@chromium.org</owner>
+  <summary>
+    The search engine used for a search performed under partnership after the
+    search engine promo dialog was shown. This is a dialog prompting the user to
+    pick a default search engine.
+  </summary>
+</histogram>
+
+<histogram name="SearchEnginePromo.NewDevices.PartnershipSearchPerformed"
+    enum="SearchEntryPoint">
+  <owner>yusufo@chromium.org</owner>
+  <summary>
+    The entry point used for a search performed under partnership after the
+    search engine promo dialog was shown. This is a dialog prompting the user to
+    pick a default search engine.
+  </summary>
+</histogram>
+
+<histogram name="SearchEnginePromo.NewDevices.SearchEngineSelection"
+    enum="OmniboxSearchEngineType">
+  <owner>yusufo@chromium.org</owner>
+  <summary>
+    The search engine selected by the user from the search engine promo. This is
+    a dialog prompting the user to pick a default search engine. The dialog was
+    shown on a device that used Chrome after it was first introduced.
+  </summary>
+</histogram>
+
+<histogram name="SearchEnginePromo.NewDevices.SecondSearchEngineListed"
+    enum="OmniboxSearchEngineType">
+  <owner>yusufo@chromium.org</owner>
+  <summary>
+    The second search engine listed in the options for search engine promo. This
+    is a dialog prompting the user to pick a default search engine. The dialog
+    was shown on a device that used Chrome after it was first introduced.
+  </summary>
+</histogram>
+
+<histogram name="SearchEnginePromo.NewDevices.ThirdSearchEngineListed"

[Alexei Svitkine (slow), 2017/05/23 15:00:16]

Please use histogram-suffixes element to make the xml definitions more concise.
You can find docs at the top of the file.
You can probably have suffixes for both NewDevice/ExistingDevices and
"First/Second/Third".

[Yusuf, 2017/05/23 17:40:53]

Done.

+    enum="OmniboxSearchEngineType">
+  <owner>yusufo@chromium.org</owner>
+  <summary>
+    The third search engine listed in the options for search engine promo. This
+    is a dialog prompting the user to pick a default search engine. The dialog
+    was shown on a device that used Chrome after it was first introduced.
+  </summary>
+</histogram>
+
+<histogram name="SearchWidget.UseAndDeviceInfo" enum="SearchWidgetUseInfo">

[Alexei Svitkine (slow), 2017/05/23 15:00:16]

You seem to be adding some new top-level prefixes, which we don't recommend
unless there will be lots of metrics underneath them.

For example, there's a top-level prefix "Search" which all of these can be
under.

[Yusuf, 2017/05/23 17:40:52]

Done.

+  <owner>yusufo@chromium.org</owner>
+  <summary>
+    The current state for search widget use and whether the device is a
+    partnership device related with the Android Search Widget.

[Alexei Svitkine (slow), 2017/05/23 15:00:16]

Please mention when it's logged. Is it once per startup? Periodically? Or when
certain interactions occur?

[Yusuf, 2017/05/23 17:40:53]

Done.

+  </summary>
+</histogram>
+
 <histogram
     name="Security.HTTPBad.NavigationStartedAfterUserWarnedAboutSensitiveInput"
     units="ms">