Adds a VerifyAuditProof method to CTLogVerifier

net/cert/merkle_audit_proof.h

Index: net/cert/merkle_audit_proof.h
diff --git a/net/cert/merkle_audit_proof.h b/net/cert/merkle_audit_proof.h
index b214891ee145ee74218f488d8d21e1965fd5c7dd..538bad2b38727ee6fb5bac9dfa768b1b15849391 100644
--- a/net/cert/merkle_audit_proof.h
+++ b/net/cert/merkle_audit_proof.h
@@ -26,12 +26,16 @@ NET_EXPORT uint64_t CalculateAuditPathLength(uint64_t leaf_index,
 struct NET_EXPORT MerkleAuditProof {
   MerkleAuditProof();
   MerkleAuditProof(uint64_t leaf_index,
+                   uint64_t tree_size,
                    const std::vector<std::string>& audit_path);
   ~MerkleAuditProof();
 
   // Index of the tree leaf in the log.
   uint64_t leaf_index = 0;
 
+  // Number of leaves in the log's tree.
+  uint64_t tree_size = 0;
+
   // Audit path nodes.
   std::vector<std::string> nodes;
 };