cc: Add predictive pre-painting.

cc/tiled_layer.h

 // Copyright 2011 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.
 
 #ifndef TiledLayerChromium_h
 #define TiledLayerChromium_h
 
 #include "CCLayerTilingData.h"
 #include "cc/layer.h"
 #include "cc/layer_texture_updater.h"
@@ skipping 65 matching lines @@
 
     bool tileOnlyNeedsPartialUpdate(UpdatableTile*);
     bool tileNeedsBufferedUpdate(UpdatableTile*);
 
     void markOcclusionsAndRequestTextures(int left, int top, int right, int bottom, const OcclusionTracker*);
 
     bool updateTiles(int left, int top, int right, int bottom, TextureUpdateQueue&, const OcclusionTracker*, RenderingStats&, bool& didPaint);
     bool haveTexturesForTiles(int left, int top, int right, int bottom, bool ignoreOcclusions);
     IntRect markTilesForUpdate(int left, int top, int right, int bottom, bool ignoreOcclusions);
     void updateTileTextures(const IntRect& paintRect, int left, int top, int right, int bottom, TextureUpdateQueue&, const OcclusionTracker*, RenderingStats&);
+    void updateScrollPrediction();
 
     UpdatableTile* tileAt(int, int) const;
     UpdatableTile* createTile(int, int);
 
     GLenum m_textureFormat;
     bool m_skipsDraw;
     bool m_failedUpdate;
 
+    // Used for predictive painting.
+    IntSize m_predictedScroll;
+    IntRect m_predictedVisibleRect;
+    IntRect m_previousVisibleRect;
+    IntSize m_previousContentBounds;
+
     TilingOption m_tilingOption;
     scoped_ptr<LayerTilingData> m_tiler;
 };
 
 }
 #endif