Add WARN_UNUSED_RESULT to crypto/hmac.h

crypto/hmac.h

Index: crypto/hmac.h
diff --git a/crypto/hmac.h b/crypto/hmac.h
index a8956ff52b959d0a27e8c52bc5674a91807f5a56..42c2e7c9969e6a9383608a4dbdce390c4e1d6b30 100644
--- a/crypto/hmac.h
+++ b/crypto/hmac.h
@@ -10,6 +10,7 @@
 #pragma once
 
 #include "base/basictypes.h"
+#include "base/compiler_specific.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/string_piece.h"
 #include "crypto/crypto_api.h"
@@ -38,11 +39,11 @@ class CRYPTO_API HMAC {
   // Initializes this instance using |key| of the length |key_length|. Call Init
   // only once. It returns false on the second or later calls.
   // TODO(abarth): key_length should be a size_t.
-  bool Init(const unsigned char* key, int key_length);
+  bool Init(const unsigned char* key, int key_length) WARN_UNUSED_RESULT;
 
   // Initializes this instance using |key|. Call Init only once. It returns
   // false on the second or later calls.
-  bool Init(const base::StringPiece& key) {
+  bool Init(const base::StringPiece& key) WARN_UNUSED_RESULT {
     return Init(reinterpret_cast<const unsigned char*>(key.data()),
                 static_cast<int>(key.size()));
   }
@@ -52,7 +53,7 @@ class CRYPTO_API HMAC {
   // returned in |digest|, which has |digest_length| bytes of storage available.
   // TODO(abarth): digest_length should be a size_t.
   bool Sign(const base::StringPiece& data, unsigned char* digest,
-            int digest_length) const;
+            int digest_length) const WARN_UNUSED_RESULT;
 
   // Verifies that the HMAC for the message in |data| equals the HMAC provided
   // in |digest|, using the algorithm supplied to the constructor and the key
@@ -62,7 +63,7 @@ class CRYPTO_API HMAC {
   // undermine the cryptographic integrity. This method does not support
   // comparing truncated HMACs.
   bool Verify(const base::StringPiece& data,
-              const base::StringPiece& digest) const;
+              const base::StringPiece& digest) const WARN_UNUSED_RESULT;
 
  private:
   HashAlgorithm hash_alg_;