Refactor: Extract common code for generating asymmetric keys to a helper.

content/child/webcrypto/openssl/rsa_key_openssl.cc

Index: content/child/webcrypto/openssl/rsa_key_openssl.cc
diff --git a/content/child/webcrypto/openssl/rsa_key_openssl.cc b/content/child/webcrypto/openssl/rsa_key_openssl.cc
index f2ab78d5d8187df395d1eb3a25279e82584c0eb6..a7f109f35482e1a504390fcef7675917925c6eaa 100644
--- a/content/child/webcrypto/openssl/rsa_key_openssl.cc
+++ b/content/child/webcrypto/openssl/rsa_key_openssl.cc
@@ -157,19 +157,15 @@ Status RsaHashedAlgorithm::GenerateKey(
     bool extractable,
     blink::WebCryptoKeyUsageMask combined_usages,
     GenerateKeyResult* result) const {
-  Status status = CheckKeyCreationUsages(
-      all_public_key_usages_ | all_private_key_usages_, combined_usages);
+  blink::WebCryptoKeyUsageMask public_usages = 0;
+  blink::WebCryptoKeyUsageMask private_usages = 0;
+
+  Status status = GetUsagesForGenerateAsymmetricKey(
+      combined_usages, all_public_key_usages_, all_private_key_usages_,
+      &public_usages, &private_usages);
   if (status.IsError())
     return status;
 
-  const blink::WebCryptoKeyUsageMask public_usages =
-      combined_usages & all_public_key_usages_;
-  const blink::WebCryptoKeyUsageMask private_usages =
-      combined_usages & all_private_key_usages_;
-
-  if (private_usages == 0)
-    return Status::ErrorCreateKeyEmptyUsages();
-
   const blink::WebCryptoRsaHashedKeyGenParams* params =
       algorithm.rsaHashedKeyGenParams();