Continue to clean c_str() calls.

components/sync_preferences/synced_pref_change_registrar.cc

Index: components/sync_preferences/synced_pref_change_registrar.cc
diff --git a/components/sync_preferences/synced_pref_change_registrar.cc b/components/sync_preferences/synced_pref_change_registrar.cc
index 3d8fa89bf23050d89e7a2403fdd708ecf2553834..5e2682ea98ad4705a334fe2bc083b1d5c388e8e9 100644
--- a/components/sync_preferences/synced_pref_change_registrar.cc
+++ b/components/sync_preferences/synced_pref_change_registrar.cc
@@ -59,7 +59,7 @@ bool SyncedPrefChangeRegistrar::IsObserved(const char* path) const {
 
 void SyncedPrefChangeRegistrar::OnSyncedPrefChanged(const std::string& path,
                                                     bool from_sync) {
-  if (pref_service_->IsManagedPreference(path.c_str()))
+  if (pref_service_->IsManagedPreference(path))
     return;
   ObserverMap::const_iterator iter = observers_.find(path);
   if (iter == observers_.end())