[profiles] Extend histogram Profile.UserAction.PerProfile

This histogram is still used by the profile metrics dashboard.

Fixed: 1121217
Change-Id: I82caf8e4c2afc738ca189ffcb57e4316e73afcb6
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2587033
Auto-Submit: David Roger <droger@chromium.org>
Reviewed-by: Alex Ilin <alexilin@chromium.org>
Commit-Queue: David Roger <droger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#836748}

tools/metrics/histograms/histograms_xml/profile/histograms.xml

@@ -578,7 +578,7 @@ reviews. Googlers can read more about this at go/gwsq-gerrit.
 </histogram>
 
 <histogram name="Profile.UserAction.PerProfile" enum="Profile"
-    expires_after="2020-10-04">
+    expires_after="2022-10-04">
   <owner>msarda@chromium.org</owner>
   <owner>tangltom@chromium.org</owner>
   <summary>
@@ -590,6 +590,9 @@ reviews. Googlers can read more about this at go/gwsq-gerrit.
     Each profile on a client is assigned a unique bucket, i.e. whenever a user
     action happens in a browser of profile x, an entry is recorded in bucket x.
 
+    This histogram is used in the profile dashboard, see go/profile-metrics and
+    go/profile-metrics-dashboard.
+
     Example: A user has 2 profiles and opens a browser window for each of them.
     When the user adds a new tab in each of the browsers, an entry is recorded
     in bucket 1 and 2, corresponding to the profiles. (Adding a new tab is a