Add new needkey event for EME.

public/platform/WebMediaPlayerClient.h

Index: public/platform/WebMediaPlayerClient.h
diff --git a/public/platform/WebMediaPlayerClient.h b/public/platform/WebMediaPlayerClient.h
index d86108ca0fd925a12f51ad944cba488751bfac6b..290bf5242aeda182e224573c4443d7d081f3671e 100644
--- a/public/platform/WebMediaPlayerClient.h
+++ b/public/platform/WebMediaPlayerClient.h
@@ -68,6 +68,7 @@ public:
     virtual void keyError(const WebString& keySystem, const WebString& sessionId, MediaKeyErrorCode, unsigned short systemCode) = 0;
     virtual void keyMessage(const WebString& keySystem, const WebString& sessionId, const unsigned char* message, unsigned messageLength, const WebURL& defaultURL) = 0;
     virtual void keyNeeded(const WebString& keySystem, const WebString& sessionId, const unsigned char* initData, unsigned initDataLength) = 0;

[acolwell GONE FROM CHROMIUM, 2014/01/13 18:19:04]

I think you should put a default implementation that forwards to the method
below here instead of in WebMediaPlayerClientImpl so that you can remove this
method on the Chromium side when you land the changes that start calling the
method below instead of this one. That should save you a CL.

[jrummell, 2014/01/13 19:01:32]

Done.

+    virtual void keyNeeded(const WebString& contentType, const unsigned char* initData, unsigned initDataLength) = 0;
     // The returned pointer is valid until closeHelperPlugin() is called.
     // Returns 0 if the plugin could not be instantiated.
     virtual WebPlugin* createHelperPlugin(const WebString& pluginType, WebFrame*) = 0;