Implement MediaKeySession.load()

public/platform/WebContentDecryptionModuleSession.h

Index: public/platform/WebContentDecryptionModuleSession.h
diff --git a/public/platform/WebContentDecryptionModuleSession.h b/public/platform/WebContentDecryptionModuleSession.h
index ab08884ff61732ada3719cee68ebb52a8e538f83..c274a0dc7e2942cc1a7daee4bdb2fa42b28d8d12 100644
--- a/public/platform/WebContentDecryptionModuleSession.h
+++ b/public/platform/WebContentDecryptionModuleSession.h
@@ -71,6 +71,7 @@ public:
     virtual void release() = 0;
 
     virtual void initializeNewSession(const WebString& initDataType, const unsigned char* initData, size_t initDataLength, const WebString& sessionType, WebContentDecryptionModuleResult);
+    virtual void load(const WebString& sessionId, WebContentDecryptionModuleResult);
     virtual void update(const unsigned char* response, size_t responseLength, WebContentDecryptionModuleResult);
     virtual void release(WebContentDecryptionModuleResult);
 };