Have a Page's MemoryPurgeController be a separate allocation also.

Source/core/page/Page.cpp

 /*
  * Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013 Apple Inc. All Rights Reserved.
  * Copyright (C) 2008 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  * This library is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ skipping 29 matching lines @@
 #include "core/layout/TextAutosizer.h"
 #include "core/page/AutoscrollController.h"
 #include "core/page/ChromeClient.h"
 #include "core/page/ContextMenuController.h"
 #include "core/page/DragController.h"
 #include "core/page/FocusController.h"
 #include "core/page/PointerLockController.h"
 #include "core/page/ValidationMessageClient.h"
 #include "core/page/scrolling/ScrollingCoordinator.h"
 #include "core/paint/DeprecatedPaintLayer.h"
+#include "platform/MemoryPurgeController.h"
 #include "platform/graphics/GraphicsLayer.h"
 #include "platform/plugins/PluginData.h"
 #include "wtf/RefCountedLeakCounter.h"
 
 namespace blink {
 
 DEFINE_DEBUG_ONLY_GLOBAL(WTF::RefCountedLeakCounter, pageCounter, ("Page"));
 
 // static
 HashSet<Page*>& Page::allPages()
@@ skipping 94 matching lines @@
 }
 
 ScrollingCoordinator* Page::scrollingCoordinator()
 {
     if (!m_scrollingCoordinator && m_settings->acceleratedCompositingEnabled())
         m_scrollingCoordinator = ScrollingCoordinator::create(this);
 
     return m_scrollingCoordinator.get();
 }
 
+MemoryPurgeController& Page::memoryPurgeController()
+{
+    if (!m_memoryPurgeController)
+        m_memoryPurgeController = MemoryPurgeController::create();
+
+    return *m_memoryPurgeController;
+}
+
 String Page::mainThreadScrollingReasonsAsText()
 {
     if (ScrollingCoordinator* scrollingCoordinator = this->scrollingCoordinator())
         return scrollingCoordinator->mainThreadScrollingReasonsAsText();
 
     return String();
 }
 
 ClientRectList* Page::nonFastScrollableRects(const LocalFrame* frame)
 {
@@ skipping 376 matching lines @@
     visitor->trace(m_dragController);
     visitor->trace(m_focusController);
     visitor->trace(m_contextMenuController);
     visitor->trace(m_pointerLockController);
     visitor->trace(m_scrollingCoordinator);
     visitor->trace(m_undoStack);
     visitor->trace(m_mainFrame);
     visitor->trace(m_validationMessageClient);
     visitor->trace(m_multisamplingChangedObservers);
     visitor->trace(m_frameHost);
+    visitor->trace(m_memoryPurgeController);
     HeapSupplementable<Page>::trace(visitor);
 #endif
-    visitor->trace(m_memoryPurgeController);
     PageLifecycleNotifier::trace(visitor);
 }
 
 void Page::willBeDestroyed()
 {
     RefPtrWillBeRawPtr<Frame> mainFrame = m_mainFrame;
 
     mainFrame->detach(FrameDetachType::Remove);
 
     if (mainFrame->isLocalFrame()) {
@@ skipping 31 matching lines @@
 {
 }
 
 Page::PageClients::~PageClients()
 {
 }
 
 template class CORE_TEMPLATE_EXPORT WillBeHeapSupplement<Page>;
 
 } // namespace blink