Disable clipping on root scroller's ancestors.

third_party/WebKit/Source/core/layout/compositing/CompositingInputsUpdater.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 "core/layout/compositing/CompositingInputsUpdater.h"
 
+#include "core/dom/Document.h"
 #include "core/frame/FrameView.h"
 #include "core/layout/LayoutBlock.h"
 #include "core/layout/LayoutView.h"
 #include "core/layout/compositing/CompositedLayerMapping.h"
 #include "core/layout/compositing/PaintLayerCompositor.h"
+#include "core/page/scrolling/RootScrollerController.h"
 #include "core/paint/PaintLayer.h"
 #include "platform/TraceEvent.h"
 
 namespace blink {
 
 CompositingInputsUpdater::CompositingInputsUpdater(PaintLayer* rootLayer)
     : m_geometryMap(UseTransforms)
     , m_rootLayer(rootLayer)
 {
 }
@@ skipping 166 matching lines @@
         info.lastScrollingAncestor = layer;
 
     if (layer->layoutObject()->hasClipRelatedProperty())
         info.hasAncestorWithClipRelatedProperty = true;
 
     if (layer->layoutObject()->hasClipPath())
         info.hasAncestorWithClipPath = true;
 
     bool hasDescendantWithClipPath = false;
     bool hasNonIsolatedDescendantWithBlendMode = false;
+    bool hasRootScrollerAsDescendant = false;
     for (PaintLayer* child = layer->firstChild(); child; child = child->nextSibling()) {
         updateRecursive(child, updateType, info);
 
+        hasRootScrollerAsDescendant |= child->hasRootScrollerAsDescendant() || (child == child->layoutObject()->document().rootScrollerController()->rootScrollerPaintLayer());
         hasDescendantWithClipPath |= child->hasDescendantWithClipPath() || child->layoutObject()->hasClipPath();
         hasNonIsolatedDescendantWithBlendMode |= (!child->stackingNode()->isStackingContext() && child->hasNonIsolatedDescendantWithBlendMode()) || child->layoutObject()->style()->hasBlendMode();
     }
 
-    layer->updateDescendantDependentCompositingInputs(hasDescendantWithClipPath, hasNonIsolatedDescendantWithBlendMode);
+    layer->updateDescendantDependentCompositingInputs(hasDescendantWithClipPath, hasNonIsolatedDescendantWithBlendMode, hasRootScrollerAsDescendant);
     layer->didUpdateCompositingInputs();
 
     m_geometryMap.popMappingsToAncestor(layer->parent());
 }
 
 #if ENABLE(ASSERT)
 
 void CompositingInputsUpdater::assertNeedsCompositingInputsUpdateBitsCleared(PaintLayer* layer)
 {
     ASSERT(!layer->childNeedsCompositingInputsUpdate());
     ASSERT(!layer->needsCompositingInputsUpdate());
 
     for (PaintLayer* child = layer->firstChild(); child; child = child->nextSibling())
         assertNeedsCompositingInputsUpdateBitsCleared(child);
 }
 
 #endif
 
 } // namespace blink