[webcryto] Validate key usages during key creation.

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 243e529bc9464d5412e20f12ff83519685d22b85..e3433fdfc1da0cc95dcad94d365e904ea3f2194a 100644
--- a/content/child/webcrypto/webcrypto_util.cc
+++ b/content/child/webcrypto/webcrypto_util.cc
@@ -179,11 +179,22 @@ bool CreateSecretKeyAlgorithm(const blink::WebCryptoAlgorithm& algorithm,
   }
 }
 
+bool ContainsKeyUsages(blink::WebCryptoKeyUsageMask a,
+                       blink::WebCryptoKeyUsageMask b) {
+  return (a & b) == b;
+}
+
 bool IsAlgorithmRsa(blink::WebCryptoAlgorithmId alg_id) {
   return alg_id == blink::WebCryptoAlgorithmIdRsaOaep ||
          alg_id == blink::WebCryptoAlgorithmIdRsaSsaPkcs1v1_5;
 }
 
+bool IsAlgorithmAsymmetric(blink::WebCryptoAlgorithmId alg_id) {
+  // TODO(padolph): include all other asymmetric algorithms once they are
+  // defined, e.g. EC and DH.
+  return IsAlgorithmRsa(alg_id);
+}
+
 }  // namespace webcrypto
 
 }  // namespace content