Allow custom deleters to opt out of self reset checks for scoped_ptr.

net/ssl/openssl_client_key_store.cc

Index: net/ssl/openssl_client_key_store.cc
diff --git a/net/ssl/openssl_client_key_store.cc b/net/ssl/openssl_client_key_store.cc
index b0b5eb3d4753d14a8ae186ba4fabfae1b927d243..67f2de9041d29eb8f5097a4a43cb2b1af8ea262a 100644
--- a/net/ssl/openssl_client_key_store.cc
+++ b/net/ssl/openssl_client_key_store.cc
@@ -51,14 +51,8 @@ OpenSSLClientKeyStore::KeyPair::KeyPair(const KeyPair& other)
 }
 
 void OpenSSLClientKeyStore::KeyPair::operator=(const KeyPair& other) {

[Jeffrey Yasskin, 2014/09/29 17:23:19]

operator= should generally be implemented with a by-value signature and a swap,
so:

void OpenSSLClientKeyStore::KeyPair::operator=(KeyPair other) {
  this->swap(other);
}

That avoids the need to duplicate the code to copy the input value.

[Ryan Sleevi, 2014/09/29 18:57:08]

Except this isn't a swap. It's a copy.

[Jeffrey Yasskin, 2014/09/29 19:20:52]

Yeah, the copy happens because the argument is passed by value, invoking the
copy constructor. Then the new value gets swapped into *this.

This saves a set of EVP_PKEY_dup() calls when the argument to operator= is a
temporary, because in that case the copy constructor doesn't need to be called
to create a by-value argument.

Search for the "copy-and-swap idiom".

-  // Use a temporary ScopedEVP_PKEY because scoped_ptr does not allow resetting
-  // to the current value, even though it's safe here.
-  crypto::ScopedEVP_PKEY public_key_tmp(EVP_PKEY_dup(other.public_key.get()));
-  crypto::ScopedEVP_PKEY private_key_tmp(EVP_PKEY_dup(other.private_key.get()));
-  public_key.reset();
-  public_key = public_key_tmp.Pass();
-  private_key.reset();
-  private_key = private_key_tmp.Pass();
+  public_key.reset(EVP_PKEY_dup(other.public_key.get()));
+  private_key.reset(EVP_PKEY_dup(other.private_key.get()));
 }
 
 int OpenSSLClientKeyStore::FindKeyPairIndex(EVP_PKEY* public_key) {