Revert of Change how the quota system computes the total poolsize for temporary storage

storage/browser/quota/client_usage_tracker.cc

Index: storage/browser/quota/client_usage_tracker.cc
diff --git a/storage/browser/quota/client_usage_tracker.cc b/storage/browser/quota/client_usage_tracker.cc
index c5a17a54ae30698492ece16b8ea3b4dd26fb9d5b..c9c46f6d1a02abd845604ebcc3522add49ec5af7 100644
--- a/storage/browser/quota/client_usage_tracker.cc
+++ b/storage/browser/quota/client_usage_tracker.cc
@@ -165,15 +165,6 @@ void ClientUsageTracker::UpdateUsageCache(const GURL& origin, int64_t delta) {
                                 AsWeakPtr(), origin));
 }
 
-int64_t ClientUsageTracker::GetCachedUsage() const {
-  int64_t usage = 0;
-  for (const auto& host_and_usage_map : cached_usage_by_host_) {
-    for (const auto& origin_and_usage : host_and_usage_map.second)
-      usage += origin_and_usage.second;
-  }
-  return usage;
-}
-
 void ClientUsageTracker::GetCachedHostsUsage(
     std::map<std::string, int64_t>* host_usage) const {
   DCHECK(host_usage);