Update MediaKeySession events to match latest EME spec

public/platform/WebContentDecryptionModuleSession.h

Index: public/platform/WebContentDecryptionModuleSession.h
diff --git a/public/platform/WebContentDecryptionModuleSession.h b/public/platform/WebContentDecryptionModuleSession.h
index 4b01c4f14ec0a770b9b9874bf0631ebea26a9ec5..1edeb07fb3bbf6c63b285d807c7e524c25a51638 100644
--- a/public/platform/WebContentDecryptionModuleSession.h
+++ b/public/platform/WebContentDecryptionModuleSession.h
@@ -47,9 +47,13 @@ public:
             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();