The Win32 /analyze builds report that:

third_party\webkit\source\core\layout\compositing\compositedlayermapping.cpp(2377) : warning C6287: Redundant code:  the left and right sub-expressions are identical.

This is correct. The original code from crrev.com/1462713002 looks like this:

    if (shouldPaintWholePage
        || (graphicsLayer != m_graphicsLayer && graphicsLayer != m_squashingLayer && graphicsLayer != m_squashingLayer && graphicsLayer != m_scrollingContentsLayer))
        return IntRect(IntPoint(), expandedIntSize(graphicsLayer->size()));

The updated code after hash 540e575dc43e718821bc4ac682735a9631e33c1f looks like this:

    if (shouldPaintWholePage
        || (graphicsLayer != m_graphicsLayer.get() && graphicsLayer != m_squashingLayer.get() && graphicsLayer != m_squashingLayer.get() && graphicsLayer != m_scrollingContentsLayer.get()))
        return wholeLayerRect;

In both cases the "graphicsLayer != m_squashingLayer" comparison is done twice. Either one should be removed or it should be changed.

Fix should be tagged with this bug number and with 427616.