Merge LogDnsClient's QueryLeafIndex and QueryAuditProof methods

components/certificate_transparency/log_dns_client.h

Index: components/certificate_transparency/log_dns_client.h
diff --git a/components/certificate_transparency/log_dns_client.h b/components/certificate_transparency/log_dns_client.h
index 6c561b072e78ceee9ecce1dfe8d77a06a8256503..92503ee003027286d1c68cc24ea9cb18cd25b867 100644
--- a/components/certificate_transparency/log_dns_client.h
+++ b/components/certificate_transparency/log_dns_client.h
@@ -32,15 +32,10 @@ namespace certificate_transparency {
 // For more information, see
 // https://github.com/google/certificate-transparency-rfcs/blob/master/dns/draft-ct-over-dns.md.
 // It must be created and deleted on the same thread. It is not thread-safe.
 class LogDnsClient : public net::NetworkChangeNotifier::DNSObserver {
  public:
-  // Invoked when a leaf index query completes.
-  // If an error occured, |net_error| will be a net::Error code, otherwise it
-  // will be net::OK and |leaf_index| will be the leaf index that was received.
-  using LeafIndexCallback =
-      base::Callback<void(int net_error, uint64_t leaf_index)>;
   // Invoked when an audit proof query completes.
   // If an error occurred, |net_error| will be a net::Error code, otherwise it
   // will be net::OK and |proof| will be the audit proof that was received.
   // The log ID of |proof| will not be set, as that is not known by this class,
   // but the leaf index will be set.
@@ -68,31 +63,30 @@ class LogDnsClient : public net::NetworkChangeNotifier::DNSObserver {
 
   // Called by NetworkChangeNotifier when the DNS config is first read.
   // The DnsClient's config will be updated in response.
   void OnInitialDNSConfigRead() override;
 
-  // Queries a CT log to discover the index of the leaf with |leaf_hash|.
-  // The log is identified by |domain_for_log|, which is the DNS name used as a
-  // suffix for all queries.
-  // The |leaf_hash| is the SHA-256 hash of a Merkle tree leaf in that log.
-  // The |callback| is invoked when the query is complete, or an error occurs.
-  void QueryLeafIndex(base::StringPiece domain_for_log,
-                      base::StringPiece leaf_hash,
-                      const LeafIndexCallback& callback);
-
-  // Queries a CT log to retrieve an audit proof for the leaf at |leaf_index|.
+  // Queries a CT log to retrieve an audit proof for the leaf with |leaf_hash|.
+  // The |leaf_hash| is the SHA-256 Merkle leaf hash (see RFC6962, section 2.1).
   // The size of the CT log tree must be provided in |tree_size|.
   // The log is identified by |domain_for_log|, which is the DNS name used as a
   // suffix for all queries.
   // The |callback| is invoked when the query is complete, or an error occurs.
   void QueryAuditProof(base::StringPiece domain_for_log,
-                       uint64_t leaf_index,
+                       base::StringPiece leaf_hash,
                        uint64_t tree_size,
                        const AuditProofCallback& callback);
 
  private:
-  void QueryLeafIndexComplete(net::DnsTransaction* transaction,
+  void QueryLeafIndex(base::StringPiece domain_for_log,
+                      base::StringPiece leaf_hash,
+                      uint64_t tree_size,
+                      const AuditProofCallback& callback);
+
+  void QueryLeafIndexComplete(base::StringPiece domain_for_log,
+                              uint64_t tree_size,
+                              net::DnsTransaction* transaction,
                               int neterror,
                               const net::DnsResponse* response);
 
   // Queries a CT log to retrieve part of an audit |proof|. The |node_index|
   // indicates which node of the audit proof/ should be requested. The CT log
@@ -120,24 +114,18 @@ class LogDnsClient : public net::NetworkChangeNotifier::DNSObserver {
 
   // Updates the |dns_client_| config using NetworkChangeNotifier.
   void UpdateDnsConfig();
 
   // A DNS query that is in flight.
-  template <typename CallbackType>
-  struct Query {
-    std::unique_ptr<net::DnsTransaction> transaction;
-    CallbackType callback;
-  };
+  struct Query;
 
   // Used to perform DNS queries.
   std::unique_ptr<net::DnsClient> dns_client_;
   // Passed to the DNS client for logging.
   net::BoundNetLog net_log_;
-  // Leaf index queries that haven't completed yet.
-  std::list<Query<LeafIndexCallback>> leaf_index_queries_;
   // Audit proof queries that haven't completed yet.
-  std::list<Query<AuditProofCallback>> audit_proof_queries_;
+  std::list<Query> audit_proof_queries_;
   // The maximum number of queries that can be in flight at one time.
   size_t max_concurrent_queries_;
   // Creates weak_ptrs to this, for callback purposes.
   base::WeakPtrFactory<LogDnsClient> weak_ptr_factory_;