[NOT FOR REVIEW] Ensure contributory behaviour for Web Push encryption.

components/gcm_driver/crypto/gcm_encryption_provider.cc

 // Copyright 2015 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.
 
 #include "components/gcm_driver/crypto/gcm_encryption_provider.h"
 
 #include <vector>
 
 #include "base/base64.h"
 #include "base/bind.h"
@@ skipping 159 matching lines @@
   std::string shared_secret;
   if (!ComputeSharedP256Secret(pair.private_key(), pair.public_key_x509(), dh,
                                &shared_secret)) {
     DLOG(ERROR) << "Unable to calculate the shared secret.";
     failure_callback.Run(DECRYPTION_FAILURE_INVALID_PUBLIC_KEY);
     return;
   }
 
   std::string plaintext;
 
-  GCMMessageCryptographer cryptographer;
+  GCMMessageCryptographer cryptographer(pair.public_key(), dh);
   if (!cryptographer.Decrypt(message.raw_data, shared_secret, salt, rs,
                              &plaintext)) {
     DLOG(ERROR) << "Unable to decrypt the incoming data.";
     failure_callback.Run(DECRYPTION_FAILURE_INVALID_PAYLOAD);
     return;
   }
 
   IncomingMessage decrypted_message;
   decrypted_message.collapse_key = message.collapse_key;
   decrypted_message.sender_id = message.sender_id;
   decrypted_message.raw_data.swap(plaintext);
   decrypted_message.decrypted = true;
 
   // There must be no data associated with the decrypted message at this point,
   // to make sure that we don't end up in an infinite decryption loop.
   DCHECK_EQ(0u, decrypted_message.data.size());
 
   success_callback.Run(decrypted_message);
 }
 
 }  // namespace gcm