Adds LogDnsClient::NotifyWhenNotThrottled

components/certificate_transparency/log_dns_client.cc

Index: components/certificate_transparency/log_dns_client.cc
diff --git a/components/certificate_transparency/log_dns_client.cc b/components/certificate_transparency/log_dns_client.cc
index cd2ef9c7b818f7cb971e2f9d2543de2bccf71d4c..dd7810d04c9072d930e3b8c6095439daf13c5178 100644
--- a/components/certificate_transparency/log_dns_client.cc
+++ b/components/certificate_transparency/log_dns_client.cc
@@ -406,10 +406,15 @@ void LogDnsClient::OnDNSChanged() {
 
 void LogDnsClient::OnInitialDNSConfigRead() {
   UpdateDnsConfig();
 }
 
+void LogDnsClient::NotifyWhenNotThrottled(const base::Closure& callback) {
+  DCHECK(HasMaxConcurrentQueriesInProgress());
+  not_throttled_callbacks_.push_back(callback);
+}
+
 // |leaf_hash| is not a const-ref to allow callers to std::move that string into
 // the method, avoiding LogDnsClient::AuditProofQuery having to make a copy.
 net::Error LogDnsClient::QueryAuditProof(
     base::StringPiece domain_for_log,
     std::string leaf_hash,
@@ -452,10 +457,16 @@ void LogDnsClient::QueryAuditProofComplete(
                    });
   DCHECK(query_iterator != audit_proof_queries_.end());
   audit_proof_queries_.erase(query_iterator);
 
   callback.Run(net_error);
+
+  // Notify interested parties that the next query will not be throttled.
+  std::list<base::Closure> callbacks = std::move(not_throttled_callbacks_);
+  for (const base::Closure& callback : callbacks) {
+    callback.Run();
+  }
 }
 
 bool LogDnsClient::HasMaxConcurrentQueriesInProgress() const {
   return max_concurrent_queries_ != 0 &&
          audit_proof_queries_.size() >= max_concurrent_queries_;