Fix test failure on Cronet Asan bot

components/cronet/host_cache_persistence_manager.cc

Index: components/cronet/host_cache_persistence_manager.cc
diff --git a/components/cronet/host_cache_persistence_manager.cc b/components/cronet/host_cache_persistence_manager.cc
index 4b47809b9395a62195debede30db63265f4915b4..97e3bdca06adaee546c63c6e3681bf3c278f7b87 100644
--- a/components/cronet/host_cache_persistence_manager.cc
+++ b/components/cronet/host_cache_persistence_manager.cc
@@ -20,6 +20,7 @@ HostCachePersistenceManager::HostCachePersistenceManager(
     : cache_(cache),
       pref_service_(pref_service),
       pref_name_(pref_name),
+      writing_pref_(false),
       delay_(delay),
       weak_factory_(this) {
   DCHECK(cache_);