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 97671a2a122d20d5d2ba37f4dffc25c238d9aea0..f123615700f5b9933b9cc3399576a7774326b29b 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -42161,6 +42161,61 @@ 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.CumulativeTotal">
+  <owner>calamity@chromium.org</owner>
+  <owner>dominickn@chromium.org</owner>
+  <summary>
+    The cumulative total site engagement accumulated by this profile over all

[calamity, 2015/09/25 07:08:33]

I would be very careful with calling this CumulativeTotal. This could all be
misinterpreted as the total number of points awarded ever (ie not accounting for
decay).

Perhaps just TotalEngagementPoints would be sufficient.

[dominickn, 2015/09/28 03:34:50]

Done.

+    time, recorded once per non-incognito startup.
+  </summary>
+</histogram>
+
+<histogram name="SiteEngagementService.EngagementPerOrigin">
+  <owner>calamity@chromium.org</owner>
+  <owner>dominickn@chromium.org</owner>
+  <summary>
+    The site engagement per origin accumulated by this profile over all time,

[calamity, 2015/09/25 07:08:33]

EngagementScoreByOrigin, perhaps?

// Counts the engagement score of each origin, recorded on non-incognito profile
startup.

[dominickn, 2015/09/28 03:34:50]

Done.

+    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="SiteIsolation.AllResponses">
   <owner>creis@chromium.org</owner>
   <summary>
@@ -70485,6 +70540,12 @@ 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"/>