Add MemoryPurgeController

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 367 matching lines @@
 {
     return m_timerAlignmentInterval;
 }
 
 void Page::setVisibilityState(PageVisibilityState visibilityState, bool isInitialState)
 {
     if (m_visibilityState == visibilityState)
         return;
     m_visibilityState = visibilityState;
 
-    if (visibilityState == PageVisibilityStateVisible)
+    if (visibilityState == PageVisibilityStateVisible) {
         setTimerAlignmentInterval(DOMTimer::visiblePageAlignmentInterval());
-    else
+        m_memoryPurgeController.pageBecameVisible();
+    } else {
         setTimerAlignmentInterval(DOMTimer::hiddenPageAlignmentInterval());
+        m_memoryPurgeController.pageBecameHidden();
+    }
 
     if (!isInitialState)
         notifyPageVisibilityChanged();
 
     if (!isInitialState && m_mainFrame && m_mainFrame->isLocalFrame())
         deprecatedLocalMainFrame()->didChangeVisibilityState();
 }
 
 PageVisibilityState Page::visibilityState() const
 {
@@ skipping 151 matching lines @@
     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);
     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