1 files changed, 11 insertions, 0 deletions
diff --git a/Source/WebCore/platform/graphics/chromium/cc/CCLayerTilingData.cpp b/Source/WebCore/platform/graphics/chromium/cc/CCLayerTilingData.cpp
index 92637fc83..27705f324 100644
--- a/Source/WebCore/platform/graphics/chromium/cc/CCLayerTilingData.cpp
+++ b/Source/WebCore/platform/graphics/chromium/cc/CCLayerTilingData.cpp
@@ -117,6 +117,17 @@ IntRect CCLayerTilingData::tileRect(const Tile* tile) const
 void CCLayerTilingData::setBounds(const IntSize& size)
 {
     m_tilingData.setTotalSize(size.width(), size.height());
+
+    // Any tiles completely outside our new bounds are invalid and should be dropped.
+    int left, top, right, bottom;
+    layerRectToTileIndices(IntRect(IntPoint(), size), left, top, right, bottom);
+    Vector<TileMapKey> invalidTileKeys;
+    for (TileMap::const_iterator it = m_tiles.begin(); it != m_tiles.end(); ++it) {
+        if (it->first.first > right || it->first.second > bottom)
+            invalidTileKeys.append(it->first);
+    }
+    for (size_t i = 0; i < invalidTileKeys.size(); ++i)
+        m_tiles.remove(invalidTileKeys[i]);
 }
 
 IntSize CCLayerTilingData::bounds() const