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

content/child/webcrypto/webcrypto_util.cc

Index: content/child/webcrypto/webcrypto_util.cc
diff --git a/content/child/webcrypto/webcrypto_util.cc b/content/child/webcrypto/webcrypto_util.cc
index 6dad83fcae7dae6c9cb0bd1ecd7b50139d56c670..d4995a93b0d37da3656fc501642491d19b508e55 100644
--- a/content/child/webcrypto/webcrypto_util.cc
+++ b/content/child/webcrypto/webcrypto_util.cc
@@ -262,6 +262,29 @@ Status GetRsaKeyGenParameters(
   return Status::Success();
 }
 
+Status GetUsagesForGenerateAsymmetricKey(
+    blink::WebCryptoKeyUsageMask combined_usages,
+    blink::WebCryptoKeyUsageMask all_public_usages,
+    blink::WebCryptoKeyUsageMask all_private_usages,
+    blink::WebCryptoKeyUsageMask* public_usages,
+    blink::WebCryptoKeyUsageMask* private_usages) {
+  *public_usages = combined_usages & all_public_usages;
+  *private_usages = combined_usages & all_private_usages;
+
+  Status status = CheckKeyCreationUsages(all_public_usages, *public_usages);
+  if (status.IsError())
+    return status;
+
+  status = CheckKeyCreationUsages(all_private_usages, *private_usages);
+  if (status.IsError())
+    return status;
+
+  if (private_usages == 0)
+    return Status::ErrorCreateKeyEmptyUsages();
+
+  return Status::Success();
+}
+
 }  // namespace webcrypto
 
 }  // namespace content