WIP - Rough draft of style observation in style of apply hooks.

Source/core/style/StyleObserver.cpp

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
-
 #include "config.h"
-#include "modules/mediasession/MediaSession.h"
+#include "core/style/StyleObserver.h"
 
 namespace blink {
 
-MediaSession* MediaSession::create()
+StyleObserver::StyleObserver() : m_weakPtrFactory(this) {}
+
+StyleObserver::~StyleObserver() {}
+
+WeakPtr<StyleObserver> StyleObserver::createWeakPtr()
 {
-    return new MediaSession;
-}
-
-void MediaSession::activate()
-{
-}
-
-void MediaSession::deactivate()
-{
+    return m_weakPtrFactory.createWeakPtr();
 }
 
 } // namespace blink