Add MemoryPurgeController

Source/core/layout/LayoutView.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  * Copyright (C) 2006 Apple Computer, Inc.
  *
  * 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,
@@ skipping 14 matching lines @@
 #include "core/CoreExport.h"
 #include "core/compositing/DisplayListCompositingBuilder.h"
 #include "core/editing/Position.h"
 #include "core/frame/FrameView.h"
 #include "core/layout/HitTestCache.h"
 #include "core/layout/HitTestResult.h"
 #include "core/layout/LayoutBlockFlow.h"
 #include "core/layout/LayoutState.h"
 #include "core/layout/PaintInvalidationState.h"
 #include "core/layout/PendingSelection.h"
+#include "platform/MemoryPurgeController.h"
 #include "platform/PODFreeListArena.h"
 #include "platform/RuntimeEnabledFeatures.h"
 #include "platform/heap/Handle.h"
 #include "platform/scroll/ScrollableArea.h"
 #include "wtf/OwnPtr.h"
 
 namespace blink {
 
 class DeprecatedPaintLayerCompositor;
 class LayoutQuote;
 
 // The root of the layout tree, corresponding to the CSS initial containing block.
 // It's dimensions match that of the logical viewport (which may be different from
 // the visible viewport in fixed-layout mode), and it is always at position (0,0)
 // relative to the document (and so isn't necessarily in view).
-class CORE_EXPORT LayoutView final : public LayoutBlockFlow {
+// TODO(bashi): Remove MemoryPurgeEventListener. This just demonstrate how
+// MemoryPurgeController works.
+class CORE_EXPORT LayoutView final : public MemoryPurgeEventListener, public LayoutBlockFlow {
 public:
     explicit LayoutView(Document*);
     ~LayoutView() override;
     void willBeDestroyed() override;
 
     // hitTest() will update layout, style and compositing first while hitTestNoLifecycleUpdate() does not.
     bool hitTest(HitTestResult&);
     bool hitTestNoLifecycleUpdate(HitTestResult&);
 
     // Returns the total count of calls to HitTest, for testing.
@@ skipping 124 matching lines @@
 
     LayoutRect visualOverflowRect() const override;
 
     // Invalidates paint for the entire view, including composited descendants, but not including child frames.
     // It is very likely you do not want to call this method.
     void setShouldDoFullPaintInvalidationForViewAndAllDescendants();
 
     void setCompositedDisplayList(PassOwnPtr<const CompositedDisplayList> compositedDisplayList) { m_compositedDisplayList = compositedDisplayList; }
     const CompositedDisplayList* compositedDisplayList() const { return m_compositedDisplayList.get(); }
 
+    void purgeMemory(MemoryPurgeMode, DeviceKind) override;
+
 private:
     void mapLocalToContainer(const LayoutBoxModelObject* paintInvalidationContainer, TransformState&, MapCoordinatesFlags = ApplyContainerFlip, bool* wasFixed = nullptr, const PaintInvalidationState* = nullptr) const override;
 
     template <typename Strategy>
     void commitPendingSelectionAlgorithm();
 
     const LayoutObject* pushMappingToContainer(const LayoutBoxModelObject* ancestorToStopAt, LayoutGeometryMap&) const override;
     void mapAbsoluteToLocalPoint(MapCoordinatesFlags, TransformState&) const override;
     void computeSelfHitTestRects(Vector<LayoutRect>&, const LayoutPoint& layerOffset) const override;
 
@@ skipping 62 matching lines @@
             m_paintInvalidationState->m_cachedOffsetsEnabled = true;
     }
 private:
     const PaintInvalidationState* m_paintInvalidationState;
     bool m_didDisable;
 };
 
 } // namespace blink
 
 #endif // LayoutView_h