[WebCrypto] Throw syntaxError if keyUsage is empty in ImportKey

content/child/webcrypto/algorithm_dispatch.cc

Index: content/child/webcrypto/algorithm_dispatch.cc
diff --git a/content/child/webcrypto/algorithm_dispatch.cc b/content/child/webcrypto/algorithm_dispatch.cc
index 1c9b409ace58e4cf87aa1dfa7014a4e46bb6aec4..cf665a3d269e7ebae715af9921c7b3268be486da 100644
--- a/content/child/webcrypto/algorithm_dispatch.cc
+++ b/content/child/webcrypto/algorithm_dispatch.cc
@@ -129,6 +129,9 @@ Status ImportKey(blink::WebCryptoKeyFormat format,
   if (status.IsError())
     return status;
 
+  if (usages == 0)

[eroman, 2014/12/05 20:45:51]

This is not correct. 

Some key types are allowed to have empty usages. For instance ECDH public keys
(https://dvcs.w3.org/hg/webcrypto-api/raw-file/tip/spec/Overview.html#ecdh)

[Habib Virji, 2014/12/08 15:05:21]

Updated. Have found usages only in AES and HMAC. 
Done.

+    return Status::ErrorImportEmptyKeyUsage();
+
   switch (format) {
     case blink::WebCryptoKeyFormatRaw:
       return impl->ImportKeyRaw(key_data, algorithm, extractable, usages, key);