Discount for inactivity timeout for recording session length

chrome/browser/metrics/desktop_engagement/desktop_engagement_service.cc

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/metrics/desktop_engagement/desktop_engagement_service.h"
 
 #include "base/bind.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/strings/string_number_conversions.h"
 #include "components/variations/variations_associated_data.h"
@@ skipping 99 matching lines @@
   in_session_ = true;
   is_first_session_ = false;
   session_start_ = base::TimeTicks::Now();
   StartTimer(inactivity_timeout_);
 }
 
 void DesktopEngagementService::EndSession() {
   in_session_ = false;
 
   base::TimeDelta delta = base::TimeTicks::Now() - session_start_;
+
+  // If timer is not running then session ended because of inactivity.
+  if (!timer_.IsRunning())
+    delta -= inactivity_timeout_;
+
   DVLOG(4) << "Logging session length of " << delta.InSeconds() << " seconds.";
 
   // Note: This metric is recorded separately for Android in
   // UmaSessionStats::UmaEndSession.
   UMA_HISTOGRAM_LONG_TIMES("Session.TotalDuration", delta);
 }
 
 void DesktopEngagementService::InitInactivityTimeout() {
   const int kDefaultInactivityTimeoutMinutes = 5;
 
   int timeout_minutes = kDefaultInactivityTimeoutMinutes;
   std::string param_value = variations::GetVariationParamValue(
       "DesktopEngagement", "inactivity_timeout");
   if (!param_value.empty())
     base::StringToInt(param_value, &timeout_minutes);
 
   inactivity_timeout_ = base::TimeDelta::FromMinutes(timeout_minutes);
 }
 
 }  // namespace metrics