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..7a00430f20308d4ad291030330abf38f1d87befb 100644
--- a/public/platform/WebMediaPlayerClient.h
+++ b/public/platform/WebMediaPlayerClient.h
@@ -67,7 +67,12 @@ public:
     virtual void keyAdded(const WebString& keySystem, const WebString& sessionId) = 0;
     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;
+    // FIXME: Remove this method after callers change to pass contentType.
+    virtual void keyNeeded(const WebString& keySystem, const WebString& sessionId, const unsigned char* initData, unsigned initDataLength)
+    {
+        keyNeeded(WebString(), initData, initDataLength);
+    }
+    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;