[Smart Lock] Measure clicks on the lock icon during Easy Unlock's trial run.

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 2445c09938d171f3362ca324dabc6dd2dabe9857..86541ab7c2ec0804623844b2120955e33880ada2 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -6491,6 +6491,23 @@ Therefore, the affected-histogram name has to have at least one dot in it.
   </summary>
 </histogram>
 
+<histogram name="EasyUnlock.TrialRun.Events" enum="EasyUnlockTrialRunEvents">
+  <owner>isherman@chromium.org</owner>
+  <owner>xiaowenx@chromium.org</owner>
+  <summary>
+    Records when the Easy Unlock trial run is launched, and when the user
+    attempts to click on the lock icon during the trial run.
+  </summary>
+  <details>
+    If a user clicks on the lock icon more than once, then the &quot;clicked
+    lock icon&quot; event counter will be incremented more than once as well.
+    Hence, the &quot;user count&quot; data shows how many users ever clicked on
+    the lock icon during the trial run. From the raw (non-&quot;user
+    count&quot;) data, we can also see whether users click on the icon multiple
+    times.
+  </details>
+</histogram>
+
 <histogram name="EasyUnlock.UnlockEvent" enum="EasyUnlockUnlockEvent">
   <obsolete>
     Deprecated 02/2015; replaced by EasyUnlock.AuthEvent.Unlock.
@@ -46156,6 +46173,11 @@ Therefore, the affected-histogram name has to have at least one dot in it.
   <int value="7" label="Help"/>
 </enum>
 
+<enum name="EasyUnlockTrialRunEvents" type="int">
+  <int value="0" label="Trial run launched"/>
+  <int value="1" label="User clicked lock icon"/>
+</enum>
+
 <enum name="EasyUnlockUnlockEvent" type="int">
   <int value="0" label="Screen unlocked (total)"/>
   <int value="1" label="Screen unlocked (via EasyUnlock)"/>