NOT FOR LANDING Introduce and use WebMediaSession

Source/core/loader/EmptyClients.cpp

Index: Source/core/loader/EmptyClients.cpp
diff --git a/Source/core/loader/EmptyClients.cpp b/Source/core/loader/EmptyClients.cpp
index d4d78adfbd30843f03fd402cb5fb6a8687d5ec43..5a8a0de4e8a73157deba015258c135b5307a019d 100644
--- a/Source/core/loader/EmptyClients.cpp
+++ b/Source/core/loader/EmptyClients.cpp
@@ -38,6 +38,7 @@
 #include "platform/Widget.h"
 #include "public/platform/WebApplicationCacheHost.h"
 #include "public/platform/WebMediaPlayer.h"
+#include "public/platform/WebMediaSession.h"
 #include "public/platform/WebServiceWorkerProvider.h"
 #include "public/platform/WebServiceWorkerProviderClient.h"
 
@@ -140,6 +141,11 @@ PassOwnPtr<WebMediaPlayer> EmptyFrameLoaderClient::createWebMediaPlayer(HTMLMedi
     return nullptr;
 }
 
+PassOwnPtr<WebMediaSession> EmptyFrameLoaderClient::createWebMediaSession()
+{
+    return nullptr;
+}
+
 void EmptyTextCheckerClient::requestCheckingOfString(PassRefPtrWillBeRawPtr<TextCheckingRequest>)
 {
 }