Add MediaKeySession.expiration attribute.

Source/modules/encryptedmedia/MediaKeySession.h

Index: Source/modules/encryptedmedia/MediaKeySession.h
diff --git a/Source/modules/encryptedmedia/MediaKeySession.h b/Source/modules/encryptedmedia/MediaKeySession.h
index 31c1a202759f25c5051e316d90a397139bba4dcd..5693d35aece5d9ad39ddecf7939bde59945761ca 100644
--- a/Source/modules/encryptedmedia/MediaKeySession.h
+++ b/Source/modules/encryptedmedia/MediaKeySession.h
@@ -70,6 +70,7 @@ public:
 
     const String& keySystem() const { return m_keySystem; }
     String sessionId() const;
+    double expiration() { return m_expiration; }

[ddorwin, 2014/10/01 23:00:53]

const function

[jrummell, 2014/10/03 00:36:10]

Done.

     ScriptPromise closed(ScriptState*);
 
     ScriptPromise generateRequest(ScriptState*, const String& initDataType, ArrayBuffer* initData);
@@ -108,6 +109,7 @@ private:
     virtual void close() OVERRIDE;
     virtual void error(MediaKeyErrorCode, unsigned long systemCode) OVERRIDE;
     virtual void error(WebContentDecryptionModuleException, unsigned long systemCode, const WebString& errorMessage) OVERRIDE;
+    virtual void expirationChanged(double updatedExpiryTimeInMS) OVERRIDE;
 
     ScriptPromise generateRequestInternal(ScriptState*, const String& initDataType, PassRefPtr<ArrayBuffer> initData);
     ScriptPromise updateInternal(ScriptState*, PassRefPtr<ArrayBuffer> response);
@@ -125,6 +127,7 @@ private:
 
     // Session properties.
     String m_sessionType;
+    double m_expiration;
 
     // Session states.
     bool m_isUninitialized;