Add WARN_UNUSED_RESULT to crypto/hmac.h

net/http/http_mac_signature.h

 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef NET_HTTP_MAC_SIGNATURE_H_
 #define NET_HTTP_MAC_SIGNATURE_H_
 #pragma once
 
 #include <string>
 
@@ skipping 21 matching lines @@
                     const base::Time& creation_date,
                     const std::string& mac_key,
                     const std::string& mac_algorithm);
 
   // Returns whether this information is valid.
   bool AddHttpInfo(const std::string& method,
                    const std::string& request_uri,
                    const std::string& host,
                    int port);
 
-  // Returns the value of the Authorization header for use in an HTTP request.
-  std::string GenerateAuthorizationHeader();
+  // Generates a value suitable for the Authorization header of an HTTP
+  // request. If successfully generated, returns true and stores the resultant
+  // header in |*header|.
+  bool GenerateAuthorizationHeader(std::string* header);
 
  private:
   FRIEND_TEST_ALL_PREFIXES(HttpMacSignatureTest, GenerateHeaderString);
   FRIEND_TEST_ALL_PREFIXES(HttpMacSignatureTest, GenerateNormalizedRequest);
   FRIEND_TEST_ALL_PREFIXES(HttpMacSignatureTest, GenerateMAC);
 
-  std::string GenerateHeaderString(const std::string& age,
-                                   const std::string& nonce);
+  bool GenerateHeaderString(const std::string& age,
+                            const std::string& nonce,
+                            std::string* header);
   std::string GenerateNormalizedRequest(const std::string& age,
                                         const std::string& nonce);
-  std::string GenerateMAC(const std::string& age,
-                          const std::string& nonce);
+  bool GenerateMAC(const std::string& age,
+                   const std::string& nonce,
+                   std::string* mac);
 
   std::string id_;
   base::Time creation_date_;
   std::string mac_key_;
   crypto::HMAC::HashAlgorithm mac_algorithm_;
 
   std::string method_;
   std::string request_uri_;
   std::string host_;
   std::string port_;
   // TODO(abarth): body_hash_
 
   DISALLOW_COPY_AND_ASSIGN(HttpMacSignature);
 };
 
 }  // namespace net
 
 #endif  // NET_HTTP_MAC_SIGNATURE_H_