Check InitDateType is supported by key system when creating session

media/blink/cdm_session_adapter.cc

Index: media/blink/cdm_session_adapter.cc
diff --git a/media/blink/cdm_session_adapter.cc b/media/blink/cdm_session_adapter.cc
index 9fe248ce56db9dfd20495330d304aee7a24b4ed1..f02ff4ede5df9044cb6fcde5ffa6ae1ecba319ac 100644
--- a/media/blink/cdm_session_adapter.cc
+++ b/media/blink/cdm_session_adapter.cc
@@ -29,6 +29,7 @@ CdmSessionAdapter::~CdmSessionAdapter() {}
 bool CdmSessionAdapter::Initialize(CdmFactory* cdm_factory,
                                    const std::string& key_system,
                                    const GURL& security_origin) {
+  key_system_ = key_system;
   key_system_uma_prefix_ =
       kMediaEME + GetKeySystemNameForUMA(key_system) + kDot;
 
@@ -110,6 +111,10 @@ CdmContext* CdmSessionAdapter::GetCdmContext() {
   return media_keys_->GetCdmContext();
 }
 
+const std::string& CdmSessionAdapter::GetKeySystem() const {
+  return key_system_;
+}
+
 const std::string& CdmSessionAdapter::GetKeySystemUMAPrefix() const {
   return key_system_uma_prefix_;
 }