Remove kDistroDict from Preferences.

chrome/browser/chromeos/login/session/user_session_manager.cc

Index: chrome/browser/chromeos/login/session/user_session_manager.cc
diff --git a/chrome/browser/chromeos/login/session/user_session_manager.cc b/chrome/browser/chromeos/login/session/user_session_manager.cc
index b304a28015feeaa3bfd72ededc929676e4417221..1063af888e4d63d7665419aa4edee59887c4cf65 100644
--- a/chrome/browser/chromeos/login/session/user_session_manager.cc
+++ b/chrome/browser/chromeos/login/session/user_session_manager.cc
@@ -1435,8 +1435,7 @@ void UserSessionManager::InitRlzImpl(Profile* profile, bool disabled) {
     local_state->SetBoolean(prefs::kRLZDisabled, disabled);
   }
   // Init the RLZ library.
-  int ping_delay = profile->GetPrefs()->GetInteger(
-      ::first_run::GetPingDelayPrefName().c_str());
+  int ping_delay = profile->GetPrefs()->GetInteger(prefs::kRlzPingDelay);
   // Negative ping delay means to send ping immediately after a first search is
   // recorded.
   rlz::RLZTracker::SetRlzDelegate(