[WebCrypto] Throw syntaxError if keyUsage is empty in ImportKey

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..603d9da7b4caa2d584c6f113618f9ea48a26ef7f 100644
--- a/content/child/webcrypto/webcrypto_util.cc
+++ b/content/child/webcrypto/webcrypto_util.cc
@@ -229,7 +229,12 @@ Status VerifyAesKeyLengthForImport(unsigned int keylen_bytes) {
 }
 
 Status CheckKeyCreationUsages(blink::WebCryptoKeyUsageMask all_possible_usages,
-                              blink::WebCryptoKeyUsageMask actual_usages) {
+                              blink::WebCryptoKeyUsageMask actual_usages,
+                              bool checkImportEmptyUsage) {

[Habib Virji, 2014/12/09 10:21:53]

Have initialized this variable to false by default, to avoid change existing
GenerateKey not requiring changes and only in case of algorithm that require
importKey usage check. 

+  // In case import key calls this function, it checks for empty usage
+  if (checkImportEmptyUsage && actual_usages == 0)
+    return Status::ErrorImportKeyEmptyUsages();
+
   if (!ContainsKeyUsages(all_possible_usages, actual_usages))
     return Status::ErrorCreateKeyBadUsages();
   return Status::Success();