Update MediaKeySession events to match latest EME spec

public/platform/WebContentDecryptionModuleSession.h

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 29 matching lines @@
 
 class BLINK_PLATFORM_EXPORT WebContentDecryptionModuleSession {
 public:
     class BLINK_PLATFORM_EXPORT Client {
     public:
         enum MediaKeyErrorCode {
             MediaKeyErrorCodeUnknown = 1,
             MediaKeyErrorCodeClient,
         };
 
-        virtual void keyAdded() = 0;
         virtual void keyError(MediaKeyErrorCode, unsigned long systemCode) = 0;
         virtual void keyMessage(const unsigned char* message, size_t messageLength, const blink::WebURL& destinationURL) = 0;
+        virtual void keyReady() = 0;
+        virtual void keyClosed() = 0;
+
+        // FIXME: Remove when all callers change to using keyReady().
+        virtual void keyAdded() { keyReady(); }
 
     protected:
         virtual ~Client();
     };
 
     virtual ~WebContentDecryptionModuleSession();
 
     virtual WebString sessionId() const = 0;
     virtual void generateKeyRequest(const WebString& mimeType, const unsigned char* initData, size_t initDataLength) = 0;
     virtual void update(const unsigned char* key, size_t keyLength) = 0;
     virtual void close() = 0;
 };
 
 } // namespace blink
 
 #endif // WebContentDecryptionModuleSession_h