Check that usage isn't empty when generateKey() is called

content/child/webcrypto/status.cc

Index: content/child/webcrypto/status.cc
diff --git a/content/child/webcrypto/status.cc b/content/child/webcrypto/status.cc
index d0a6caff87748164d931edaa78c1d1888beff065..b1da01d00504e5a1ab5008ebebfba012e11c70dd 100644
--- a/content/child/webcrypto/status.cc
+++ b/content/child/webcrypto/status.cc
@@ -252,6 +252,11 @@ Status Status::ErrorCreateKeyBadUsages() {
                 "Cannot create a key using the specified key usages.");
 }
 
+Status Status::ErrorCreateKeyEmptyUsages() {
+  return Status(blink::WebCryptoErrorTypeSyntax,
+                "Usages cannot be empty when creating a key.");
+}
+
 Status Status::ErrorImportedEcKeyIncorrectCurve() {
   return Status(
       blink::WebCryptoErrorTypeData,