Validate Service Certificates Before Accepting Them

(This is a merge of http://go/wvgerrit/14630)

To create a better flow when an application sets a service certificate
manually, we will now validate the certificate when it is given to us,
and if it is invalid, we will not allow the property to be set.

Bug: 21307186
Change-Id: If980ad075604223fc962a859fae93e98d86a7f4f

libwvdrmengine/cdm/src/wv_content_decryption_module.cpp

@@ -5,6 +5,7 @@
 #include "cdm_client_property_set.h"
 #include "cdm_engine.h"
 #include "initialization_data.h"
+#include "license.h"
 #include "log.h"
 #include "properties.h"
 #include "wv_cdm_constants.h"
@@ -37,6 +38,11 @@ bool WvContentDecryptionModule::IsWebm(const std::string& init_data_type) {
   return InitializationData(init_data_type).is_webm();
 }
 
+bool WvContentDecryptionModule::IsValidServiceCertificate(
+    const std::string& certificate) {
+  return CdmLicense::VerifySignedServiceCertificate(certificate) == NO_ERROR;
+}
+
 CdmResponseType WvContentDecryptionModule::OpenSession(
     const CdmKeySystem& key_system, CdmClientPropertySet* property_set,
     const std::string& origin, WvCdmEventListener* event_listener,