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 cb6856a7f03c5e35f56726b814796aaf046e1233..d147a442284ad7a1812ffb58ea1d8acaad6a4dd1 100644
--- a/Source/web/FrameLoaderClientImpl.cpp
+++ b/Source/web/FrameLoaderClientImpl.cpp
@@ -56,6 +56,8 @@
 #include "modules/device_orientation/DeviceOrientationController.h"
 #include "modules/encryptedmedia/HTMLMediaElementEncryptedMedia.h"
 #include "modules/gamepad/NavigatorGamepad.h"
+#include "modules/mediasession/HTMLMediaElementMediaSession.h"
+#include "modules/mediasession/MediaSession.h"
 #include "modules/serviceworkers/NavigatorServiceWorker.h"
 #include "modules/storage/DOMWindowStorageController.h"
 #include "modules/vr/NavigatorVRDevice.h"
@@ -76,6 +78,7 @@
 #include "public/platform/WebURL.h"
 #include "public/platform/WebURLError.h"
 #include "public/platform/WebVector.h"
+#include "public/platform/modules/mediasession/WebMediaSession.h"
 #include "public/web/WebAutofillClient.h"
 #include "public/web/WebContentSettingsClient.h"
 #include "public/web/WebDOMEvent.h"
@@ -759,10 +762,22 @@ PassOwnPtr<WebMediaPlayer> FrameLoaderClientImpl::createWebMediaPlayer(
     if (!webFrame || !webFrame->client())
         return nullptr;
 
+    WebMediaSession* webMediaSession = 0;
+    if (MediaSession* session = HTMLMediaElementMediaSession::session(htmlMediaElement))
+        webMediaSession = session->webMediaSession();
+
     HTMLMediaElementEncryptedMedia& encryptedMedia = HTMLMediaElementEncryptedMedia::from(htmlMediaElement);
     return adoptPtr(webFrame->client()->createMediaPlayer(webFrame, url,
         client, &encryptedMedia,
-        encryptedMedia.contentDecryptionModule()));
+        encryptedMedia.contentDecryptionModule(), webMediaSession));
+}
+
+PassOwnPtr<WebMediaSession> FrameLoaderClientImpl::createWebMediaSession()
+{
+    if (!m_webFrame->client())
+        return nullptr;
+
+    return adoptPtr(m_webFrame->client()->createMediaSession(m_webFrame));
 }
 
 ObjectContentType FrameLoaderClientImpl::objectContentType(