Revert of Remove FOUC avoidance from BlockPainter and DeprecatedPaintLayerPainter.

Source/core/paint/DeprecatedPaintLayerPainter.cpp

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "config.h"
 #include "core/paint/DeprecatedPaintLayerPainter.h"
 
 #include "core/frame/Settings.h"
 #include "core/layout/ClipPathOperation.h"
 #include "core/layout/LayoutBlock.h"
@@ skipping 13 matching lines @@
 #include "core/paint/Transform3DRecorder.h"
 #include "platform/graphics/GraphicsLayer.h"
 #include "platform/graphics/paint/ClipPathRecorder.h"
 #include "platform/graphics/paint/ClipRecorder.h"
 #include "platform/graphics/paint/CompositingDisplayItem.h"
 #include "platform/graphics/paint/Transform3DDisplayItem.h"
 #include "wtf/Optional.h"
 
 namespace blink {
 
+static inline bool shouldSuppressPaintingLayer(DeprecatedPaintLayer* layer)
+{
+    // Avoid painting descendants of the root layer when stylesheets haven't loaded. This eliminates FOUC.
+    // It's ok not to draw, because later on, when all the stylesheets do load, updateStyleSelector on the Document
+    // will do a full paintInvalidationForWholeLayoutObject().
+    if (layer->layoutObject()->document().didLayoutWithPendingStylesheets() && !layer->isRootLayer() && !layer->layoutObject()->isDocumentElement())
+        return true;
+
+    return false;
+}
+
 void DeprecatedPaintLayerPainter::paint(GraphicsContext* context, const LayoutRect& damageRect, const GlobalPaintFlags globalPaintFlags, LayoutObject* paintingRoot, PaintLayerFlags paintFlags)
 {
     DeprecatedPaintLayerPaintingInfo paintingInfo(&m_paintLayer, LayoutRect(enclosingIntRect(damageRect)), globalPaintFlags, LayoutSize(), paintingRoot);
     if (shouldPaintLayerInSoftwareMode(globalPaintFlags, paintFlags))
         paintLayer(context, paintingInfo, paintFlags);
 }
 
 static ShouldRespectOverflowClip shouldRespectOverflowClip(PaintLayerFlags paintFlags, const LayoutObject* layoutObject)
 {
     return (paintFlags & PaintLayerPaintingOverflowContents || (paintFlags & PaintLayerPaintingChildClippingMaskPhase && layoutObject->hasClipPath())) ? IgnoreOverflowClip : RespectOverflowClip;
 }
 
 void DeprecatedPaintLayerPainter::paintLayer(GraphicsContext* context, const DeprecatedPaintLayerPaintingInfo& paintingInfo, PaintLayerFlags paintFlags)
 {
     // https://code.google.com/p/chromium/issues/detail?id=343772
     DisableCompositingQueryAsserts disabler;
 
     if (m_paintLayer.compositingState() != NotComposited) {
         if (paintingInfo.globalPaintFlags() & GlobalPaintFlattenCompositingLayers) {
             // FIXME: ok, but what about GlobalPaintFlattenCompositingLayers? That's for printing and drag-image.
             // FIXME: why isn't the code here global, as opposed to being set on each paintLayer() call?
             paintFlags |= PaintLayerUncachedClipRects;
         }
     }
 
     // Non self-painting leaf layers don't need to be painted as their layoutObject() should properly paint itself.
     if (!m_paintLayer.isSelfPaintingLayer() && !m_paintLayer.hasSelfPaintingLayerDescendant())
         return;
 
+    if (shouldSuppressPaintingLayer(&m_paintLayer))
+        return;
+
     // If this layer is totally invisible then there is nothing to paint.
     if (!m_paintLayer.layoutObject()->opacity())
         return;
 
     if (m_paintLayer.paintsWithTransparency(paintingInfo.globalPaintFlags()))
         paintFlags |= PaintLayerHaveTransparency;
 
     LayerFixedPositionRecorder fixedPositionRecorder(*context, *m_paintLayer.layoutObject());
 
     // PaintLayerAppliedTransform is used in LayoutReplica, to avoid applying the transform twice.
@@ skipping 515 matching lines @@
     if (!m_paintLayer.containsDirtyOverlayScrollbars())
         return;
 
     DeprecatedPaintLayerPaintingInfo paintingInfo(&m_paintLayer, LayoutRect(enclosingIntRect(damageRect)), paintFlags, LayoutSize(), paintingRoot);
     paintLayer(context, paintingInfo, PaintLayerPaintingOverlayScrollbars);
 
     m_paintLayer.setContainsDirtyOverlayScrollbars(false);
 }
 
 } // namespace blink