Merge 76864 - 2011-01-27 Adrienne Walker <enne@google.com>...

Source/WebCore/platform/graphics/chromium/LayerTilerChromium.cpp

 /*
  * Copyright (C) 2010 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
@@ skipping 281 matching lines @@
     CGContextTranslateCTM(m_cgContext.get(), -paintRect.x(), -paintRect.y());
     painter.paint(*m_graphicsContext, paintRect);
 
     // Get the contents of the updated rect.
     ASSERT(static_cast<int>(CGBitmapContextGetWidth(m_cgContext.get())) == paintRect.width() && static_cast<int>(CGBitmapContextGetHeight(m_cgContext.get())) == paintRect.height());
     uint8_t* paintPixels = static_cast<uint8_t*>(canvasPixels.data());
 #else
 #error "Need to implement for your platform."
 #endif
 
+    // Painting could cause compositing to get turned off, which may cause the tiler to become invalidated mid-update.
+    if (!m_tiles.size())
+        return;
+
     for (int j = top; j <= bottom; ++j) {
         for (int i = left; i <= right; ++i) {
             Tile* tile = m_tiles[tileIndex(i, j)].get();
             if (!tile->dirty())
                 continue;
 
             // Calculate page-space rectangle to copy from.
             IntRect sourceRect = tileContentRect(i, j);
             const IntPoint anchor = sourceRect.location();
             sourceRect.intersect(layerRectToContentRect(tile->m_dirtyLayerRect));
@@ skipping 38 matching lines @@
     }
 }
 
 void LayerTilerChromium::setLayerPosition(const IntPoint& layerPosition)
 {
     m_layerPosition = layerPosition;
 }
 
 void LayerTilerChromium::draw(const IntRect& contentRect)
 {
-    if (m_skipsDraw)
+    if (m_skipsDraw || !m_tiles.size())
         return;
 
     // We reuse the shader program used by ContentLayerChromium.
     GraphicsContext3D* context = layerRendererContext();
     const ContentLayerChromium::SharedValues* contentLayerValues = layerRenderer()->contentLayerSharedValues();
     layerRenderer()->useShader(contentLayerValues->contentShaderProgram());
     GLC(context, context->uniform1i(contentLayerValues->shaderSamplerLocation(), 0));
 
     int left, top, right, bottom;
     contentRectToTileIndices(contentRect, left, top, right, bottom);
@@ skipping 43 matching lines @@
     IntRect layerRect = contentRectToLayerRect(contentRect);
     IntSize layerSize = IntSize(layerRect.right(), layerRect.bottom());
 
     IntSize newSize = layerSize.expandedTo(m_layerSize);
     resizeLayer(newSize);
 }
 
 } // namespace WebCore
 
 #endif // USE(ACCELERATED_COMPOSITING)