NOT FOR LANDING Introduce and use WebMediaSession

Source/web/FrameLoaderClientImpl.cpp

Index: Source/web/FrameLoaderClientImpl.cpp
diff --git a/Source/web/FrameLoaderClientImpl.cpp b/Source/web/FrameLoaderClientImpl.cpp
index 8885c1bea329eddb6bb9b0024a2d5bef414fb7cf..67076621d103e91125906119a412fa69e2015f7a 100644
--- a/Source/web/FrameLoaderClientImpl.cpp
+++ b/Source/web/FrameLoaderClientImpl.cpp
@@ -68,6 +68,7 @@
 #include "platform/plugins/PluginData.h"
 #include "public/platform/Platform.h"
 #include "public/platform/WebApplicationCacheHost.h"
+#include "public/platform/WebMediaSession.h"
 #include "public/platform/WebMimeRegistry.h"
 #include "public/platform/WebRTCPeerConnectionHandler.h"
 #include "public/platform/WebSecurityOrigin.h"
@@ -796,6 +797,14 @@ PassOwnPtr<WebMediaPlayer> FrameLoaderClientImpl::createWebMediaPlayer(
         encryptedMedia.contentDecryptionModule()));
 }
 
+PassOwnPtr<WebMediaSession> FrameLoaderClientImpl::createWebMediaSession()
+{
+    if (!m_webFrame->client())
+        return nullptr;
+
+    return adoptPtr(m_webFrame->client()->createMediaSession(m_webFrame));
+}
+
 ObjectContentType FrameLoaderClientImpl::objectContentType(
     const KURL& url,
     const String& explicitMimeType,