UMA track signed in duration at signout

components/signin/core/browser/signin_manager.cc

 // Copyright 2014 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 "components/signin/core/browser/signin_manager.h"
 
 #include <string>
 #include <vector>
 
+#include "base/metrics/histogram.h"
 #include "base/prefs/pref_service.h"
 #include "base/strings/string_split.h"
 #include "base/strings/string_util.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/time/time.h"
 #include "components/signin/core/browser/profile_oauth2_token_service.h"
 #include "components/signin/core/browser/signin_account_id_helper.h"
 #include "components/signin/core/browser/signin_client.h"
 #include "components/signin/core/browser/signin_internals_util.h"
 #include "components/signin/core/browser/signin_manager_cookie_helper.h"
@@ skipping 174 matching lines @@
   }
 
   if (prohibit_signout_) {
     DVLOG(1) << "Ignoring attempt to sign out while signout is prohibited";
     return;
   }
 
   ClearTransientSigninData();
 
   const std::string username = GetAuthenticatedUsername();
+  const base::Time signin_time =
+      base::Time::FromInternalValue(
+          client_->GetPrefs()->GetInt64(prefs::kSignedInTime));
   clear_authenticated_username();
   client_->GetPrefs()->ClearPref(prefs::kGoogleServicesUsername);
+  client_->GetPrefs()->ClearPref(prefs::kSignedInTime);
   client_->ClearSigninScopedDeviceId();
 
   // Erase (now) stale information from AboutSigninInternals.
   NotifyDiagnosticsObservers(USERNAME, "");
 
+  // Determine the duration the user was logged in and log that to UMA.
+  if (!signin_time.is_null()) {
+    base::TimeDelta signed_in_duration = base::Time::Now() - signin_time;

[Alexei Svitkine (slow), 2014/08/12 14:41:49]

Note: Be aware that if the user's machine time changes, you'll get inconsistent
results. But presumably that should be a minority of users.

[Mike Lerman, 2014/08/12 18:07:10]

I assume this will indeed be a very small proportion of users.

+    UMA_HISTOGRAM_COUNTS("Signin.SignedInDurationBeforeSignout",
+                         signed_in_duration.InMinutes()));

[Roger Tawa OOO till Jul 10th, 2014/08/12 14:14:52]

Should we be paranoid and check that delta > 0?

[Alexei Svitkine (slow), 2014/08/12 14:41:49]

I believe it should automatically go in the underflow bucket, so its "OK" in the
sense that there won't be any crashes etc.

[Mike Lerman, 2014/08/12 18:07:10]

Acknowledged.

+  }
+
   // Revoke all tokens before sending signed_out notification, because there
   // may be components that don't listen for token service events when the
   // profile is not connected to an account.
   LOG(WARNING) << "Revoking refresh token on server. Reason: sign out, "
                << "IsSigninAllowed: " << IsSigninAllowed();
   token_service_->RevokeAllCredentials();
 
   FOR_EACH_OBSERVER(Observer, observer_list_, GoogleSignedOut(username));
 }
 
@@ skipping 144 matching lines @@
 
   password_.clear();                           // Don't need it anymore.
   DisableOneClickSignIn(client_->GetPrefs());  // Don't ever offer again.
 }
 
 void SigninManager::ProhibitSignout(bool prohibit_signout) {
   prohibit_signout_ = prohibit_signout;
 }
 
 bool SigninManager::IsSignoutProhibited() const { return prohibit_signout_; }