Convert the encryption header parsers to be iterator-based.

components/gcm_driver/crypto/gcm_encryption_provider.cc

Index: components/gcm_driver/crypto/gcm_encryption_provider.cc
diff --git a/components/gcm_driver/crypto/gcm_encryption_provider.cc b/components/gcm_driver/crypto/gcm_encryption_provider.cc
index 0e3873eb094f3b6e05a1f02ba9ce416ec3f06f2d..d7d1141df106334bc61800ffc147916028c55efc 100644
--- a/components/gcm_driver/crypto/gcm_encryption_provider.cc
+++ b/components/gcm_driver/crypto/gcm_encryption_provider.cc
@@ -85,32 +85,30 @@ void GCMEncryptionProvider::DecryptMessage(
   DCHECK(encryption_header != message.data.end());
   DCHECK(crypto_key_header != message.data.end());
 
-  std::vector<EncryptionHeaderValues> encryption_header_values;
-  if (!ParseEncryptionHeader(encryption_header->second,
-                             &encryption_header_values)) {
+  EncryptionHeaderIterator encryption_header_iterator(
+      encryption_header->second.begin(), encryption_header->second.end());
+  if (!encryption_header_iterator.GetNext()) {
     DLOG(ERROR) << "Unable to parse the value of the Encryption header";
     failure_callback.Run(DECRYPTION_FAILURE_INVALID_ENCRYPTION_HEADER);
     return;
   }
 
-  if (encryption_header_values.size() != 1u ||
-      encryption_header_values[0].salt.size() !=
+  if (encryption_header_iterator.salt().size() !=
           GCMMessageCryptographer::kSaltSize) {
     DLOG(ERROR) << "Invalid values supplied in the Encryption header";
     failure_callback.Run(DECRYPTION_FAILURE_INVALID_ENCRYPTION_HEADER);
     return;
   }
 
-  std::vector<CryptoKeyHeaderValues> crypto_key_header_values;
-  if (!ParseCryptoKeyHeader(crypto_key_header->second,
-                            &crypto_key_header_values)) {
+  CryptoKeyHeaderIterator crypto_key_header_iterator(
+      crypto_key_header->second.begin(), crypto_key_header->second.end());
+  if (!crypto_key_header_iterator.GetNext()) {
     DLOG(ERROR) << "Unable to parse the value of the Crypto-Key header";
     failure_callback.Run(DECRYPTION_FAILURE_INVALID_CRYPTO_KEY_HEADER);
     return;
   }
 
-  if (crypto_key_header_values.size() != 1u ||
-      !crypto_key_header_values[0].dh.size()) {
+  if (!crypto_key_header_iterator.dh().size()) {

[Ryan Sleevi, 2015/12/08 00:22:00]

Use .empty(), not .size(), to test for empty STL containers.

[Peter Beverloo, 2015/12/16 21:09:57]

Done.

     DLOG(ERROR) << "Invalid values supplied in the Crypto-Key header";
     failure_callback.Run(DECRYPTION_FAILURE_INVALID_CRYPTO_KEY_HEADER);
     return;
@@ -120,9 +118,9 @@ void GCMEncryptionProvider::DecryptMessage(
       app_id, base::Bind(&GCMEncryptionProvider::DecryptMessageWithKey,
                          weak_ptr_factory_.GetWeakPtr(), message,
                          success_callback, failure_callback,
-                         encryption_header_values[0].salt,
-                         crypto_key_header_values[0].dh,
-                         encryption_header_values[0].rs));
+                         encryption_header_iterator.salt(),
+                         crypto_key_header_iterator.dh(),
+                         encryption_header_iterator.rs()));
 }
 
 void GCMEncryptionProvider::DidGetPublicKey(const std::string& app_id,