Revert of List message decryption failures on chrome://gcm-internals

components/gcm_driver/crypto/gcm_encryption_provider.h

Index: components/gcm_driver/crypto/gcm_encryption_provider.h
diff --git a/components/gcm_driver/crypto/gcm_encryption_provider.h b/components/gcm_driver/crypto/gcm_encryption_provider.h
index 9eec22cd9063c0060f279607879e9a30f76df134..c545276830675daac047e9739bf84ddfc2a5f478 100644
--- a/components/gcm_driver/crypto/gcm_encryption_provider.h
+++ b/components/gcm_driver/crypto/gcm_encryption_provider.h
@@ -58,9 +58,6 @@
   // Callback to be invoked when a message cannot be decoded.
   using DecryptionFailedCallback = base::Callback<void(DecryptionFailure)>;
 
-  // Converts |reason| to a string describing the details of said reason.
-  static std::string ToDecryptionFailureDetailsString(DecryptionFailure reason);
-
   GCMEncryptionProvider();
   ~GCMEncryptionProvider();