[Content suggestions] Report updates in the UI to UMA.

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 eb1845ae819354ab7ddb37a2a7a9cc30aa7c4b4d..6d2728d569a51d24d60546d5fce5d89b9700a77f 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -39279,6 +39279,14 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="NewTabPage.ContentSuggestions.UIUpdateResult"
+    enum="ContentSuggestionsUIUpdateResult">
+  <owner>jkrcal@chromium.org</owner>
+  <summary>
+    Android: The result of updating the list of content suggestions in the UI.
+  </summary>
+</histogram>
+
 <histogram name="NewTabPage.ContentSuggestions.UsageTimeLocal">
   <owner>markusheintz@chromium.org</owner>
   <summary>
@@ -81411,6 +81419,17 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   <int value="1" label="Explicit"/>
 </enum>
 
+<enum name="ContentSuggestionsUIUpdateResult" type="int">
+  <int value="0" label="Success (appended)"/>
+  <int value="1" label="Success (no suggestion seen)"/>
+  <int value="2" label="Success (1 suggestion seen)"/>
+  <int value="3" label="Success (2 suggestions seen)"/>
+  <int value="4" label="Success (3 suggestions seen)"/>
+  <int value="5" label="Success (more than 3 suggestions seen)"/>
+  <int value="6" label="Fail (all suggestions seen)"/>
+  <int value="7" label="Fail (updates disabled)"/>
+</enum>
+
 <enum name="ContentType" type="int">
   <int value="-1" label="Invalid setting"/>
   <int value="0" label="Cookies setting"/>