Don't composite layers with an invisible frameview.

third_party/WebKit/Source/core/layout/compositing/PaintLayerCompositor.cpp

Index: third_party/WebKit/Source/core/layout/compositing/PaintLayerCompositor.cpp
diff --git a/third_party/WebKit/Source/core/layout/compositing/PaintLayerCompositor.cpp b/third_party/WebKit/Source/core/layout/compositing/PaintLayerCompositor.cpp
index 16650e0a8010342a0719e344c0d6a99757e6305b..c9f2a9ad6d3d62665438a106cfbc030d17c02cf0 100644
--- a/third_party/WebKit/Source/core/layout/compositing/PaintLayerCompositor.cpp
+++ b/third_party/WebKit/Source/core/layout/compositing/PaintLayerCompositor.cpp
@@ -767,8 +767,13 @@ void PaintLayerCompositor::updateDirectCompositingReasons(PaintLayer* layer)
 
 bool PaintLayerCompositor::canBeComposited(const PaintLayer* layer) const
 {
-    const bool hasCompositorAnimation = m_compositingReasonFinder.requiresCompositingForAnimation(*layer->layoutObject()->style());
-    return m_hasAcceleratedCompositing && (hasCompositorAnimation || !layer->subtreeIsInvisible()) && layer->isSelfPaintingLayer() && !layer->layoutObject()->isLayoutFlowThread();
+    LayoutObject* layoutObject = layer->layoutObject();
+    FrameView* frameView = layoutObject->frameView();

[chrishtr, 2016/01/21 22:49:18]

Just layer->layoutObject()->frameView() is ok.

[wkorman, 2016/01/22 00:19:56]

Done. I pulled layoutObject into a local variable to shorten two references in
line 775 and 776, so I've restored those as well.

+    if (frameView && !frameView->isVisible()) {
+        return false;

[chrishtr, 2016/01/21 22:49:18]

Add a comment explaining this situation. e.g.:

Elements within an invisible frame need not be composited, because they are not
drawn.

[wkorman, 2016/01/22 00:19:56]

Done.

+    }
+    const bool hasCompositorAnimation = m_compositingReasonFinder.requiresCompositingForAnimation(*layoutObject->style());
+    return m_hasAcceleratedCompositing && (hasCompositorAnimation || !layer->subtreeIsInvisible()) && layer->isSelfPaintingLayer() && !layoutObject->isLayoutFlowThread();
 }
 
 // Return true if the given layer is a stacking context and has compositing child