If the root layer is drawn using GL_LINEAR, then compositing/checkerboard.html fails. To the naked eye, the checkerboard rendering looks the same as the reference image, but the imagediff shows slight imperfections exist near the right edge of the image. This is currently worked around by turning off border texels on the root layer (which causes GL_NEAREST to be used instead). The test failure can be reproduced by always passing in CCLayerTilingData::HasBorderTexels to createTiler() in TiledLayerChromium::prepareToUpdate().