RSAPrivateKey vector push_back cleanups.

crypto/rsa_private_key_win.cc

Index: crypto/rsa_private_key_win.cc
diff --git a/crypto/rsa_private_key_win.cc b/crypto/rsa_private_key_win.cc
index f0e64772caaee9ea7bb01f3ba130ed084535a0f3..f7363422db8b18928e95c8b2bd98690a0bc7f3d4 100644
--- a/crypto/rsa_private_key_win.cc
+++ b/crypto/rsa_private_key_win.cc
@@ -222,9 +222,7 @@ bool RSAPrivateKey::ExportPublicKey(std::vector<uint8>* output) {
     return false;
   }
 
-  for (size_t i = 0; i < encoded_length; ++i)
-    output->push_back(encoded[i]);
-
+  output->assign(encoded.get(), encoded.get() + encoded_length);
   return true;
 }