1. @DomName('StorageQuotaCallback')
  2. @Experimental()
void StorageQuotaCallback(int grantedQuotaInBytes)

Source 

@DomName('StorageQuotaCallback')
// http://www.w3.org/TR/quota-api/#idl-def-StorageQuotaCallback
@Experimental()
typedef void StorageQuotaCallback(int grantedQuotaInBytes);