Revert "Move some scroll invalidations to the paint invalidation phase"

Source/core/frame/FrameView.cpp

Index: Source/core/frame/FrameView.cpp
diff --git a/Source/core/frame/FrameView.cpp b/Source/core/frame/FrameView.cpp
index 0aead4777869975461aa32155082b51948005ade..068f3d14dc6d5f6e2926d31a6a3a56af7af2cb86 100644
--- a/Source/core/frame/FrameView.cpp
+++ b/Source/core/frame/FrameView.cpp
@@ -1244,18 +1244,12 @@ void FrameView::scrollContentsIfNeededRecursive()
     }
 }
 
-// FIXME: If we had a flag to force invalidations in a whole subtree, we could get rid of this function (crbug.com/410097).
-static void setShouldDoFullPaintInvalidationIncludingNonCompositingDescendants(const RenderLayer* layer)
+void FrameView::scrollContentsIfNeeded()
 {
-    layer->renderer()->setShouldDoFullPaintInvalidation(true);
-
-    for (RenderLayer* child = layer->firstChild(); child; child = child->nextSibling()) {
-        // Don't include paint invalidation rects for composited child layers; they will paint themselves and have a different origin.
-        if (child->isPaintInvalidationContainer())
-            continue;
-
-        setShouldDoFullPaintInvalidationIncludingNonCompositingDescendants(child);
-    }
+    bool didScroll = !pendingScrollDelta().isZero();
+    ScrollView::scrollContentsIfNeeded();
+    if (didScroll)
+        updateFixedElementPaintInvalidationRectsAfterScroll();
 }
 
 bool FrameView::scrollContentsFastPath(const IntSize& scrollDelta)
@@ -1268,6 +1262,7 @@ bool FrameView::scrollContentsFastPath(const IntSize& scrollDelta)
         return true;
     }
 
+    Region regionToUpdate;
     ViewportConstrainedObjectSet::const_iterator end = m_viewportConstrainedObjects->end();
     for (ViewportConstrainedObjectSet::const_iterator it = m_viewportConstrainedObjects->begin(); it != end; ++it) {
         RenderObject* renderer = *it;
@@ -1275,7 +1270,8 @@ bool FrameView::scrollContentsFastPath(const IntSize& scrollDelta)
         ASSERT(renderer->hasLayer());
         RenderLayer* layer = toRenderBoxModelObject(renderer)->layer();
 
-        if (layer->isPaintInvalidationContainer())
+        CompositingState state = layer->compositingState();
+        if (state == PaintsIntoOwnBacking || state == PaintsIntoGroupedBacking)
             continue;
 
         if (layer->subtreeIsInvisible())
@@ -1286,10 +1282,39 @@ bool FrameView::scrollContentsFastPath(const IntSize& scrollDelta)
         if (layer->hasAncestorWithFilterOutsets())
             return false;
 
-        setShouldDoFullPaintInvalidationIncludingNonCompositingDescendants(layer);
+        IntRect updateRect = pixelSnappedIntRect(layer->paintInvalidator().paintInvalidationRectIncludingNonCompositingDescendants());
+
+        const RenderLayerModelObject* repaintContainer = layer->renderer()->containerForPaintInvalidation();
+        if (repaintContainer && !repaintContainer->isRenderView()) {
+            // Invalidate the old and new locations of fixed position elements that are not drawn into the RenderView.
+            updateRect.moveBy(scrollPosition());
+            IntRect previousRect = updateRect;
+            previousRect.move(scrollDelta);
+            // FIXME: Rather than uniting the rects, we should just issue both invalidations.
+            updateRect.unite(previousRect);
+            layer->renderer()->invalidatePaintUsingContainer(repaintContainer, updateRect, InvalidationScroll);
+        } else {
+            // Coalesce the paint invalidations that will be issued to the renderView.
+            updateRect = contentsToRootView(updateRect);
+            if (!updateRect.isEmpty())
+                regionToUpdate.unite(updateRect);
+        }
     }
 
     InspectorInstrumentation::didScroll(page());
+
+    // Invalidate the old and new locations of fixed position elements that are drawn into the RenderView.
+    Vector<IntRect> subRectsToUpdate = regionToUpdate.rects();
+    size_t viewportConstrainedObjectsCount = subRectsToUpdate.size();
+    for (size_t i = 0; i < viewportConstrainedObjectsCount; ++i) {
+        IntRect updateRect = subRectsToUpdate[i];
+        IntRect scrolledRect = updateRect;
+        scrolledRect.move(-scrollDelta);
+        updateRect.unite(scrolledRect);
+        // FIXME: We should be able to issue these invalidations separately and before we actually scroll.
+        renderView()->layer()->paintInvalidator().setBackingNeedsPaintInvalidationInRect(rootViewToContents(updateRect));
+    }
+
     return true;
 }
 
@@ -1519,6 +1544,32 @@ void FrameView::updateLayersAndCompositingAfterScrollIfNeeded()
     }
 }
 
+void FrameView::updateFixedElementPaintInvalidationRectsAfterScroll()
+{
+    if (!hasViewportConstrainedObjects())
+        return;
+
+    // Update the paint invalidation rects for fixed elements after scrolling and invalidation to reflect
+    // the new scroll position.
+    ViewportConstrainedObjectSet::const_iterator end = m_viewportConstrainedObjects->end();
+    for (ViewportConstrainedObjectSet::const_iterator it = m_viewportConstrainedObjects->begin(); it != end; ++it) {
+        RenderObject* renderer = *it;
+        // m_viewportConstrainedObjects should not contain non-viewport constrained objects.
+        ASSERT(renderer->style()->hasViewportConstrainedPosition());
+
+        // Fixed items should always have layers.
+        ASSERT(renderer->hasLayer());
+
+        RenderLayer* layer = toRenderBoxModelObject(renderer)->layer();
+
+        // Don't need to do this for composited fixed items.
+        if (layer->compositingState() == PaintsIntoOwnBacking)
+            continue;
+
+        layer->paintInvalidator().computePaintInvalidationRectsIncludingNonCompositingDescendants();
+    }
+}
+
 void FrameView::updateCompositedSelectionBoundsIfNeeded()
 {
     if (!RuntimeEnabledFeatures::compositedSelectionUpdatesEnabled())
@@ -2516,8 +2567,7 @@ void FrameView::updateLayoutAndStyleForPainting()
 
     updateWidgetPositionsIfNeeded();
 
-    RenderView* view = renderView();
-    if (view) {
+    if (RenderView* view = renderView()) {
         TRACE_EVENT_INSTANT1(TRACE_DISABLED_BY_DEFAULT("devtools.timeline"), "UpdateLayerTree", "frame", m_frame.get());
         // FIXME(361045): remove InspectorInstrumentation calls once DevTools Timeline migrates to tracing.
         InspectorInstrumentation::willUpdateLayerTree(m_frame.get());
@@ -2530,13 +2580,11 @@ void FrameView::updateLayoutAndStyleForPainting()
         updateCompositedSelectionBoundsIfNeeded();
 
         InspectorInstrumentation::didUpdateLayerTree(m_frame.get());
-    }
 
-    scrollContentsIfNeededRecursive();
-
-    if (view)
         invalidateTreeIfNeededRecursive();
+    }
 
+    scrollContentsIfNeededRecursive();
     ASSERT(lifecycle().state() == DocumentLifecycle::PaintInvalidationClean);
 }