Write "logout-started" event on next boot.

Writing logout-started on process exit is unstable.
So moving it to next boot.

BUG=352130
TEST=manual

Review URL: https://codereview.chromium.org/303233004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@274649 0039d316-1c4b-4281-b951-d872f2087c98
diff --git a/chrome/browser/chromeos/preferences.cc b/chrome/browser/chromeos/preferences.cc
index 2fa7fe0..d0e04df 100644
--- a/chrome/browser/chromeos/preferences.cc
+++ b/chrome/browser/chromeos/preferences.cc
@@ -83,6 +83,7 @@
   registry->RegisterBooleanPref(prefs::kOwnerPrimaryMouseButtonRight, false);
   registry->RegisterBooleanPref(prefs::kOwnerTapToClickEnabled, true);
   registry->RegisterBooleanPref(prefs::kVirtualKeyboardEnabled, false);
+  registry->RegisterStringPref(prefs::kLogoutStartedLast, std::string());
 }
 
 // static