Add new needkey event for EME.

Source/web/WebMediaPlayerClientImpl.cpp

Index: Source/web/WebMediaPlayerClientImpl.cpp
diff --git a/Source/web/WebMediaPlayerClientImpl.cpp b/Source/web/WebMediaPlayerClientImpl.cpp
index 8e29cda8730ec5538cdefac1d3d6aab31d93e230..dee905a95ff218f1a7ae63b323b36f85dd04fe96 100644
--- a/Source/web/WebMediaPlayerClientImpl.cpp
+++ b/Source/web/WebMediaPlayerClientImpl.cpp
@@ -142,7 +142,13 @@ void WebMediaPlayerClientImpl::keyMessage(const WebString& keySystem, const WebS
 
 void WebMediaPlayerClientImpl::keyNeeded(const WebString& keySystem, const WebString& sessionId, const unsigned char* initData, unsigned initDataLength)
 {
-    m_client->mediaPlayerKeyNeeded(keySystem, sessionId, initData, initDataLength);
+    // FIXME: remove after callers change to pass contentType.
+    m_client->mediaPlayerKeyNeeded(WebString(), initData, initDataLength);
+}
+
+void WebMediaPlayerClientImpl::keyNeeded(const WebString& contentType, const unsigned char* initData, unsigned initDataLength)
+{
+    m_client->mediaPlayerKeyNeeded(contentType, initData, initDataLength);
 }
 
 WebPlugin* WebMediaPlayerClientImpl::createHelperPlugin(const WebString& pluginType, WebFrame* frame)