ExtensionStorageMonitor: use smaller, self-registering StorageObservers

storage/browser/quota/quota_manager.cc

Index: storage/browser/quota/quota_manager.cc
diff --git a/storage/browser/quota/quota_manager.cc b/storage/browser/quota/quota_manager.cc
index 518ca1d6d398d6989a671ff45b70933aff4d544c..74d2de64bb2ff1c01ceac2ced53f80ec96510852 100644
--- a/storage/browser/quota/quota_manager.cc
+++ b/storage/browser/quota/quota_manager.cc
@@ -1109,12 +1109,6 @@ void QuotaManager::RemoveStorageObserver(StorageObserver* observer) {
   storage_monitor_->RemoveObserver(observer);
 }
 
-void QuotaManager::RemoveStorageObserverForFilter(
-    StorageObserver* observer, const StorageObserver::Filter& filter) {
-  DCHECK(observer);
-  storage_monitor_->RemoveObserverForFilter(observer, filter);
-}
-
 QuotaManager::~QuotaManager() {
   proxy_->manager_ = NULL;
   for (auto* client : clients_)