Removed an unused private variable in db_impl.h

Summary: Removed an unused private variable in db_impl.h

Test Plan: make db_test

Reviewers: sdong, anthony, igor

Reviewed By: igor

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D38925

db/db_impl.cc

@@ -312,7 +312,6 @@ DBImpl::~DBImpl() {
   while (bg_compaction_scheduled_ || bg_flush_scheduled_ || notifying_events_) {
     bg_cv_.Wait();
   }
-  listeners_.clear();
   flush_scheduler_.Clear();
 
   while (!flush_queue_.empty()) {

db/db_impl.h

@@ -626,9 +626,6 @@ class DBImpl : public DB {
   // Indicate DB was opened successfully
   bool opened_successfully_;
 
-  // The list of registered event listeners.
-  std::list<EventListener*> listeners_;
-
   // count how many events are currently being notified.
   int notifying_events_;