Record shutdown type UMA

To investigate how frequently unclean shutdown is performed.

Start recording a new UMA Shutdown.ShutdownType.
Update prefs::kShutdownType when Chrome is performing unclean shutdown with SessionEnding().

BUG=644649

Review-Url: https://codereview.chromium.org/2318373003
Cr-Commit-Position: refs/heads/master@{#419123}

chrome/browser/browser_shutdown.cc

@@ -170,6 +170,21 @@ bool ShutdownPreThreadsStop() {
   if (metrics)
     metrics->RecordCompletedSessionEnd();
 
+  bool restart_last_session = RecordShutdownInfoPrefs();
+
+  prefs->CommitPendingWrite();
+
+#if defined(ENABLE_RLZ)
+  // Cleanup any statics created by RLZ. Must be done before NotificationService
+  // is destroyed.
+  rlz::RLZTracker::CleanupRlz();
+#endif
+
+  return restart_last_session;
+}
+
+bool RecordShutdownInfoPrefs() {
+  PrefService* prefs = g_browser_process->local_state();
   if (g_shutdown_type > NOT_VALID && g_shutdown_num_processes > 0) {
     // Record the shutdown info so that we can put it into a histogram at next
     // startup.
@@ -179,22 +194,13 @@ bool ShutdownPreThreadsStop() {
                       g_shutdown_num_processes_slow);
   }
 
-  // Check local state for the restart flag so we can restart the session below.
+  // Check local state for the restart flag so we can restart the session later.
   bool restart_last_session = false;
   if (prefs->HasPrefPath(prefs::kRestartLastSessionOnShutdown)) {
     restart_last_session =
         prefs->GetBoolean(prefs::kRestartLastSessionOnShutdown);
     prefs->ClearPref(prefs::kRestartLastSessionOnShutdown);
   }
-
-  prefs->CommitPendingWrite();
-
-#if defined(ENABLE_RLZ)
-  // Cleanup any statics created by RLZ. Must be done before NotificationService
-  // is destroyed.
-  rlz::RLZTracker::CleanupRlz();
-#endif
-
   return restart_last_session;
 }
 
@@ -327,6 +333,8 @@ void ReadLastShutdownInfo() {
   prefs->SetInteger(prefs::kShutdownNumProcesses, 0);
   prefs->SetInteger(prefs::kShutdownNumProcessesSlow, 0);
 
+  UMA_HISTOGRAM_ENUMERATION("Shutdown.ShutdownType", type, kNumShutdownTypes);
+
   // Read and delete the file on the file thread.
   BrowserThread::PostTask(
       BrowserThread::FILE, FROM_HERE,

chrome/browser/browser_shutdown.h

@@ -36,6 +36,8 @@ enum ShutdownType {
   END_SESSION
 };
 
+constexpr int kNumShutdownTypes = END_SESSION + 1;
+
 void RegisterPrefs(PrefRegistrySimple* registry);
 
 // Called when the browser starts shutting down so that we can measure shutdown
@@ -52,6 +54,10 @@ ShutdownType GetShutdownType();
 // Returns true if the session should be restarted.
 bool ShutdownPreThreadsStop();
 
+// Records the shutdown related prefs, and returns true if the browser should be
+// restarted on exit.
+bool RecordShutdownInfoPrefs();
+
 // Performs the remaining shutdown tasks after all threads but the
 // main thread have been stopped.  This includes deleting g_browser_process.
 //

chrome/browser/lifetime/application_lifetime.cc

@@ -307,6 +307,13 @@ void SessionEnding() {
 
   browser_shutdown::OnShutdownStarting(browser_shutdown::END_SESSION);
 
+  // In a clean shutdown, browser_shutdown::OnShutdownStarting sets
+  // g_shutdown_type, and browser_shutdown::ShutdownPreThreadsStop calls
+  // RecordShutdownInfoPrefs to update the pref with the value. However, here
+  // the process is going to exit without calling ShutdownPreThreadsStop.
+  // Instead, here we call RecordShutdownInfoPrefs to record the shutdown info.
+  browser_shutdown::RecordShutdownInfoPrefs();
+
   content::NotificationService::current()->Notify(
       chrome::NOTIFICATION_CLOSE_ALL_BROWSERS_REQUEST,
       content::NotificationService::AllSources(),

tools/metrics/histograms/histograms.xml

@@ -55863,6 +55863,11 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="Shutdown.ShutdownType" enum="ShutdownType">
+  <owner>hashimoto@chromium.org</owner>
+  <summary>The type of the last shutdown.</summary>
+</histogram>
+
 <histogram name="Signin" enum="SigninHelperFlow">
   <owner>mlerman@chromium.org</owner>
   <summary>
@@ -94936,6 +94941,13 @@ To add a new entry, add it with any value and run test to compute valid value.
   <int value="6" label="Dark resume failed"/>
 </enum>
 
+<enum name="ShutdownType" type="int">
+  <int value="0" label="Not valid">Invalid value.</int>
+  <int value="1" label="Window close">The last browser window was closed.</int>
+  <int value="2" label="Browser exit">User clicked on the Exit menu item.</int>
+  <int value="3" label="End session">OS is logging off or shutting down.</int>
+</enum>
+
 <enum name="SideloadUIEvents" type="int">
   <int value="0" label="Extension installed"/>
   <int value="1" label="Extension ignored"/>