Add UMA metrics to the site engagement service.

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 1468912af806f6adf6524a8ad134ef010390a570..228dd9157b96f3511fee527b32b60dfb42b7667b 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -42181,6 +42181,61 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   <summary>Number of retries until the final response was recorded.</summary>
 </histogram>
 
+<histogram name="SiteEngagementService.EngagementByOrigin">
+  <owner>calamity@chromium.org</owner>
+  <owner>dominickn@chromium.org</owner>
+  <summary>
+    Counts the engagement score of each origin, recorded once per non-incognito
+    startup.
+  </summary>
+</histogram>
+
+<histogram name="SiteEngagementService.EngagementType"
+    enum="SiteEngagementServiceEngagementType">
+  <owner>calamity@chromium.org</owner>
+  <owner>dominickn@chromium.org</owner>
+  <summary>
+    The type of engagement (navigation, user input, etc.) which caused an
+    accumulation in site engagement.
+  </summary>
+</histogram>
+
+<histogram name="SiteEngagementService.OriginsEngaged">
+  <owner>calamity@chromium.org</owner>
+  <owner>dominickn@chromium.org</owner>
+  <summary>
+    The total number of origins with a non-zero site engagement score for this
+    profile, once per non-incognito startup.
+  </summary>
+</histogram>
+
+<histogram name="SiteEngagementService.OriginsWithMaxDailyEngagement">
+  <owner>calamity@chromium.org</owner>
+  <owner>dominickn@chromium.org</owner>
+  <summary>
+    The number of origins which have reached the capped maximum site engagement
+    accumulation in a day, recorded each time an origin reaches the cap.
+  </summary>
+</histogram>
+
+<histogram name="SiteEngagementService.OriginsWithMaxEngagement">
+  <owner>calamity@chromium.org</owner>
+  <owner>dominickn@chromium.org</owner>
+  <summary>
+    The number of origins which reach the capped maximum site engagement total,
+    recorded each time an origin reaches the cap.
+  </summary>
+</histogram>
+
+<histogram name="SiteEngagementService.TotalEngagement">
+  <owner>calamity@chromium.org</owner>
+  <owner>dominickn@chromium.org</owner>
+  <summary>
+    The total site engagement accumulated by this profile, recorded once per
+    non-incognito startup.
+  </summary>
+</histogram>
+
 <histogram name="SiteIsolation.AllResponses">
   <owner>creis@chromium.org</owner>
   <summary>
@@ -70520,6 +70575,12 @@ To add a new entry, add it with any value and run test to compute valid value.
   <int value="3" label="Fresh index with cache updated since backend start"/>
 </enum>
 
+<enum name="SiteEngagementServiceEngagementType" type="int">
+  <int value="0" label="Navigation"/>
+  <int value="1" label="Keypress"/>
+  <int value="2" label="Mouse"/>
+</enum>
+
 <enum name="SiteIsolationMimeType" type="int">
   <int value="0" label="HTML"/>
   <int value="1" label="XML"/>