Add Incognito profile lifetime duration metrics.

UMA stats collection is added for the life time of incognito profile.

Bug: 966747
Change-Id: Ic83f3f88589e9fb6088f140575b38cc1c0798bf6
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1628747
Commit-Queue: Ramin Halavati <rhalavati@chromium.org>
Auto-Submit: Ramin Halavati <rhalavati@chromium.org>
Reviewed-by: Brian White <bcwhite@chromium.org>
Reviewed-by: Mihai Sardarescu <msarda@chromium.org>
Cr-Commit-Position: refs/heads/master@{#664753}

chrome/browser/profiles/off_the_record_profile_impl.cc

@@ -11,6 +11,7 @@
 #include "base/command_line.h"
 #include "base/compiler_specific.h"
 #include "base/files/file_path.h"
+#include "base/metrics/histogram_functions.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/string_util.h"
 #include "base/task/post_task.h"
@@ -242,6 +243,14 @@ OffTheRecordProfileImpl::~OffTheRecordProfileImpl() {
   // This must be called before ProfileIOData::ShutdownOnUIThread but after
   // other profile-related destroy notifications are dispatched.
   ShutdownStoragePartitions();
+
+  // Store incognito lifetime histogram.
+  if (!IsGuestSession()) {
+    auto duration = base::Time::Now() - start_time_;
+    base::UmaHistogramCustomCounts(
+        "Profile.Incognito.Lifetime", duration.InMinutes(), 1,
+        base::TimeDelta::FromDays(28).InMinutes(), 100);
+  }
 }
 
 void OffTheRecordProfileImpl::InitIoData() {

tools/metrics/histograms/histograms.xml

@@ -100916,6 +100916,16 @@ uploading your change for review.
   <summary>Size of the history database.</summary>
 </histogram>
 
+<histogram name="Profile.Incognito.Lifetime" units="minutes"
+    expires_after="M80">
+  <owner>rhalavati@chromium.org</owner>
+  <owner>msramek@chromium.org</owner>
+  <summary>
+    This histogram records the lifetime duration of incognito profiles. It is
+    recorded once an off the record profile for an incognito session is closed.
+  </summary>
+</histogram>
+
 <histogram name="Profile.InitProfileUserPrefs.OutsideUserDir" enum="BooleanHit"
     expires_after="M77">
   <owner>anthonyvd@chromium.org</owner>