Enable compositing for opaque scrolling content on low DPI screens

third_party/WebKit/Source/core/frame/FrameView.cpp

Index: third_party/WebKit/Source/core/frame/FrameView.cpp
diff --git a/third_party/WebKit/Source/core/frame/FrameView.cpp b/third_party/WebKit/Source/core/frame/FrameView.cpp
index 3fa8e63c185b071c4f343796b89e2d2f3ac3c1be..3a0f9d0278f3beff4054040ba44b831d931ae214 100644
--- a/third_party/WebKit/Source/core/frame/FrameView.cpp
+++ b/third_party/WebKit/Source/core/frame/FrameView.cpp
@@ -170,7 +170,7 @@ FrameView::FrameView(LocalFrame* frame)
     , m_suppressAdjustViewSize(false)
     , m_allowsLayoutInvalidationAfterLayoutClean(true)
 {
-    ASSERT(m_frame);
+    DCHECK(m_frame);
     init();
 }
 
@@ -193,7 +193,9 @@ FrameView* FrameView::create(LocalFrame* frame, const IntSize& initialSize)
 
 FrameView::~FrameView()
 {
-    ASSERT(m_hasBeenDisposed);
+#if ENABLE(ASSERT)
+    DCHECK(m_hasBeenDisposed);
+#endif
 }
 
 DEFINE_TRACE(FrameView)
@@ -266,7 +268,7 @@ void FrameView::init()
 
 void FrameView::dispose()
 {
-    RELEASE_ASSERT(!isInPerformLayout());
+    CHECK(!isInPerformLayout());
 
     if (ScrollAnimatorBase* scrollAnimator = existingScrollAnimator())
         scrollAnimator->cancelAnimation();
@@ -538,7 +540,7 @@ void FrameView::adjustViewSize()
     if (layoutViewItem.isNull())
         return;
 
-    ASSERT(m_frame->view() == this);
+    DCHECK(m_frame->view() == this);
 
     const IntRect rect = layoutViewItem.documentRect();
     const IntSize& size = rect.size();
@@ -637,7 +639,7 @@ void FrameView::updateAcceleratedCompositingSettings()
 void FrameView::recalcOverflowAfterStyleChange()
 {
     LayoutViewItem layoutViewItem = this->layoutViewItem();
-    RELEASE_ASSERT(!layoutViewItem.isNull());
+    CHECK(!layoutViewItem.isNull());
     if (!layoutViewItem.needsOverflowRecalcAfterStyleChange())
         return;
 
@@ -685,7 +687,7 @@ bool FrameView::usesCompositedScrolling() const
     LayoutViewItem layoutView = this->layoutViewItem();
     if (layoutView.isNull())
         return false;
-    if (m_frame->settings() && m_frame->settings()->preferCompositingToLCDTextEnabled())
+    if (layoutView.layer()->needsCompositedScrolling())

[chrishtr, 2016/07/27 19:26:00]

I don't think this will work, because the view is special and doesn't have
overflow clipping.

[Stephen Chennney, 2016/07/28 13:55:38]

Done.

         return layoutView.compositor()->inCompositingMode();
     return false;
 }
@@ -778,7 +780,7 @@ inline void FrameView::forceLayoutParentViewIfNeeded()
     ownerLayoutObject->setNeedsLayoutAndPrefWidthsRecalcAndFullPaintInvalidation(LayoutInvalidationReason::Unknown);
 
     // Synchronously enter layout, to layout the view containing the host object/embed/iframe.
-    ASSERT(frameView);
+    DCHECK(frameView);
     frameView->layout();
 }
 
@@ -872,7 +874,7 @@ std::unique_ptr<TracedValue> FrameView::analyzerCounters()
 
 void FrameView::performLayout(bool inSubtreeLayout)
 {
-    ASSERT(inSubtreeLayout || m_layoutSubtreeRootList.isEmpty());
+    DCHECK(inSubtreeLayout || m_layoutSubtreeRootList.isEmpty());
 
     TRACE_EVENT_BEGIN1(PERFORM_LAYOUT_TRACE_CATEGORIES, "FrameView::performLayout",
         "contentsHeightBeforeLayout", layoutViewItem().documentRect().height());
@@ -880,7 +882,7 @@ void FrameView::performLayout(bool inSubtreeLayout)
 
     ScriptForbiddenScope forbidScript;
 
-    ASSERT(!isInPerformLayout());
+    DCHECK(!isInPerformLayout());
     lifecycle().advanceTo(DocumentLifecycle::InPerformLayout);
 
     // performLayout is the actual guts of layout().
@@ -945,9 +947,9 @@ void FrameView::scheduleOrPerformPostLayoutTasks()
 void FrameView::layout()
 {
     // We should never layout a Document which is not in a LocalFrame.
-    ASSERT(m_frame);
-    ASSERT(m_frame->view() == this);
-    ASSERT(m_frame->page());
+    DCHECK(m_frame);
+    DCHECK(m_frame->view() == this);
+    DCHECK(m_frame->page());
 
     ScriptForbiddenScope forbidScript;
 
@@ -1061,7 +1063,7 @@ void FrameView::layout()
         if (!inSubtreeLayout && !document->printing())
             adjustViewSizeAndLayout();
 
-        ASSERT(m_layoutSubtreeRootList.isEmpty());
+        DCHECK(m_layoutSubtreeRootList.isEmpty());
     } // Reset m_layoutSchedulingEnabled to its previous value.
     checkDoesNotNeedLayout();
 
@@ -1114,9 +1116,9 @@ void FrameView::invalidateTreeIfNeeded(const PaintInvalidationState& paintInvali
 
     lifecycle().advanceTo(DocumentLifecycle::InPaintInvalidation);
 
-    RELEASE_ASSERT(!layoutViewItem().isNull());
+    CHECK(!layoutViewItem().isNull());
     LayoutViewItem rootForPaintInvalidation = layoutViewItem();
-    ASSERT(!rootForPaintInvalidation.needsLayout());
+    DCHECK(!rootForPaintInvalidation.needsLayout());
 
     TRACE_EVENT1("blink", "FrameView::invalidateTree", "root", rootForPaintInvalidation.debugName().ascii());
 
@@ -1132,7 +1134,7 @@ void FrameView::invalidateTreeIfNeeded(const PaintInvalidationState& paintInvali
 
 void FrameView::invalidatePaintIfNeeded(const PaintInvalidationState& paintInvalidationState)
 {
-    RELEASE_ASSERT(!layoutViewItem().isNull());
+    CHECK(!layoutViewItem().isNull());
     if (!m_frame->settings() || !m_frame->settings()->rootLayerScrolls())
         invalidatePaintOfScrollControlsIfNeeded(paintInvalidationState);
 
@@ -1257,10 +1259,10 @@ void FrameView::updateWidgetGeometries()
 
 void FrameView::addPartToUpdate(LayoutEmbeddedObject& object)
 {
-    ASSERT(isInPerformLayout());
+    DCHECK(isInPerformLayout());
     // Tell the DOM element that it needs a widget update.
     Node* node = object.node();
-    ASSERT(node);
+    DCHECK(node);
     if (isHTMLObjectElement(*node) || isHTMLEmbedElement(*node))
         toHTMLPlugInElement(node)->setNeedsWidgetUpdate(true);
 
@@ -1280,7 +1282,7 @@ void FrameView::setDisplayMode(WebDisplayMode mode)
 
 void FrameView::setMediaType(const AtomicString& mediaType)
 {
-    ASSERT(m_frame->document());
+    DCHECK(m_frame->document());
     m_frame->document()->mediaQueryAffectingValueChanged();
     m_mediaType = mediaType;
 }
@@ -1314,7 +1316,7 @@ bool FrameView::contentsInCompositedLayer() const
 
 void FrameView::addBackgroundAttachmentFixedObject(LayoutObject* object)
 {
-    ASSERT(!m_backgroundAttachmentFixedObjects.contains(object));
+    DCHECK(!m_backgroundAttachmentFixedObjects.contains(object));
 
     m_backgroundAttachmentFixedObjects.add(object);
     if (ScrollingCoordinator* scrollingCoordinator = this->scrollingCoordinator())
@@ -1323,7 +1325,7 @@ void FrameView::addBackgroundAttachmentFixedObject(LayoutObject* object)
 
 void FrameView::removeBackgroundAttachmentFixedObject(LayoutObject* object)
 {
-    ASSERT(m_backgroundAttachmentFixedObjects.contains(object));
+    DCHECK(m_backgroundAttachmentFixedObjects.contains(object));
 
     m_backgroundAttachmentFixedObjects.remove(object);
     if (ScrollingCoordinator* scrollingCoordinator = this->scrollingCoordinator())
@@ -1420,8 +1422,8 @@ bool FrameView::invalidateViewportConstrainedObjects()
     for (const auto& viewportConstrainedObject : *m_viewportConstrainedObjects) {
         LayoutObject* layoutObject = viewportConstrainedObject;
         LayoutItem layoutItem = LayoutItem(layoutObject);
-        ASSERT(layoutItem.style()->hasViewportConstrainedPosition());
-        ASSERT(layoutItem.hasLayer());
+        DCHECK(layoutItem.style()->hasViewportConstrainedPosition());
+        DCHECK(layoutItem.hasLayer());
         PaintLayer* layer = LayoutBoxModel(layoutItem).layer();
 
         if (layer->isPaintInvalidationContainer())
@@ -1473,7 +1475,7 @@ void FrameView::scrollContentsSlowPath(const IntRect& updateRect)
     // We need full invalidation during slow scrolling. For slimming paint, full invalidation
     // of the LayoutView is not enough. We also need to invalidate all of the objects.
     // FIXME: Find out what are enough to invalidate in slow path scrolling. crbug.com/451090#9.
-    ASSERT(!layoutViewItem().isNull());
+    DCHECK(!layoutViewItem().isNull());
     if (contentsInCompositedLayer())
         layoutViewItem().layer()->compositedLayerMapping()->setContentsNeedDisplay();
     else
@@ -1482,7 +1484,7 @@ void FrameView::scrollContentsSlowPath(const IntRect& updateRect)
 
     if (contentsInCompositedLayer()) {
         IntRect updateRect = visibleContentRect();
-        ASSERT(!layoutViewItem().isNull());
+        DCHECK(!layoutViewItem().isNull());
         // FIXME: We should not allow paint invalidation out of paint invalidation state. crbug.com/457415
         DisablePaintInvalidationStateAsserts disabler;
         layoutViewItem().invalidatePaintRectangle(LayoutRect(updateRect));
@@ -1530,7 +1532,7 @@ void FrameView::processUrlFragment(const KURL& url, UrlFragmentBehavior behavior
 
 bool FrameView::processUrlFragmentHelper(const String& name, UrlFragmentBehavior behavior)
 {
-    ASSERT(m_frame->document());
+    DCHECK(m_frame->document());
 
     if (behavior == UrlFragmentScroll && !m_frame->document()->isRenderingReady()) {
         m_frame->document()->setGotoAnchorNeededAfterStylesheetsLoad(true);
@@ -1578,7 +1580,7 @@ bool FrameView::processUrlFragmentHelper(const String& name, UrlFragmentBehavior
 
 void FrameView::setFragmentAnchor(Node* anchorNode)
 {
-    ASSERT(anchorNode);
+    DCHECK(anchorNode);
     m_fragmentAnchor = anchorNode;
 
     // We need to update the layout tree before scrolling.
@@ -1640,7 +1642,7 @@ IntSize FrameView::layoutSize(IncludeScrollbarsInRect scrollbarInclusion) const
 
 void FrameView::setLayoutSize(const IntSize& size)
 {
-    ASSERT(!layoutSizeFixedToFrameSize());
+    DCHECK(!layoutSizeFixedToFrameSize());
 
     setLayoutSizeInternal(size);
 }
@@ -1726,7 +1728,7 @@ void FrameView::updateCompositedSelectionIfNeeded()
     TRACE_EVENT0("blink", "FrameView::updateCompositedSelectionIfNeeded");
 
     Page* page = frame().page();
-    ASSERT(page);
+    DCHECK(page);
 
     CompositedSelection selection;
     LocalFrame* focusedFrame = page->focusController().focusedFrame();
@@ -1824,7 +1826,7 @@ bool FrameView::hasOrthogonalWritingModeRoots() const
 void FrameView::layoutOrthogonalWritingModeRoots()
 {
     for (auto& root : m_orthogonalWritingModeRootList.ordered()) {
-        ASSERT(root->isBox() && toLayoutBox(*root).isOrthogonalWritingModeRoot());
+        DCHECK(root->isBox() && toLayoutBox(*root).isOrthogonalWritingModeRoot());
         if (!root->needsLayout()
             || root->isOutOfFlowPositioned()
             || root->isColumnSpanAll()
@@ -2034,7 +2036,7 @@ bool FrameView::updateWidgets()
 {
     // This is always called from updateWidgetsTimerFired.
     // m_updateWidgetsTimer should only be scheduled if we have widgets to update.
-    // Thus I believe we can stop checking isEmpty here, and just ASSERT isEmpty:
+    // Thus I believe we can stop checking isEmpty here, and just DCHECK isEmpty:
     // FIXME: This assert has been temporarily removed due to https://crbug.com/430344
     if (m_nestedLayoutCount > 1 || m_partUpdateSet.isEmpty())
         return true;
@@ -2070,7 +2072,7 @@ bool FrameView::updateWidgets()
 
 void FrameView::updateWidgetsTimerFired(Timer<FrameView>*)
 {
-    ASSERT(!isInPerformLayout());
+    DCHECK(!isInPerformLayout());
     m_updateWidgetsTimer.stop();
     for (unsigned i = 0; i < maxUpdateWidgetsIterations; ++i) {
         if (updateWidgets())
@@ -2080,7 +2082,7 @@ void FrameView::updateWidgetsTimerFired(Timer<FrameView>*)
 
 void FrameView::flushAnyPendingPostLayoutTasks()
 {
-    ASSERT(!isInPerformLayout());
+    DCHECK(!isInPerformLayout());
     if (m_postLayoutTasksTimer.isActive())
         performPostLayoutTasks();
     if (m_updateWidgetsTimer.isActive())
@@ -2089,7 +2091,7 @@ void FrameView::flushAnyPendingPostLayoutTasks()
 
 void FrameView::scheduleUpdateWidgetsIfNecessary()
 {
-    ASSERT(!isInPerformLayout());
+    DCHECK(!isInPerformLayout());
     if (m_updateWidgetsTimer.isActive() || m_partUpdateSet.isEmpty())
         return;
     m_updateWidgetsTimer.startOneShot(0, BLINK_FROM_HERE);
@@ -2100,8 +2102,8 @@ void FrameView::performPostLayoutTasks()
     // FIXME: We can reach here, even when the page is not active!
     // http/tests/inspector/elements/html-link-import.html and many other
     // tests hit that case.
-    // We should ASSERT(isActive()); or at least return early if we can!
-    ASSERT(!isInPerformLayout()); // Always before or after performLayout(), part of the highest-level layout() call.
+    // We should DCHECK(isActive()); or at least return early if we can!
+    DCHECK(!isInPerformLayout()); // Always before or after performLayout(), part of the highest-level layout() call.
     TRACE_EVENT0("blink,benchmark", "FrameView::performPostLayoutTasks");
 
     m_postLayoutTasksTimer.stop();
@@ -2109,7 +2111,7 @@ void FrameView::performPostLayoutTasks()
     m_frame->selection().setCaretRectNeedsUpdate();
     m_frame->selection().updateAppearance();
 
-    ASSERT(m_frame->document());
+    DCHECK(m_frame->document());
 
     FontFaceSet::didLayout(*m_frame->document());
     // Cursor update scheduling is done by the local root, which is the main frame if there
@@ -2139,17 +2141,17 @@ void FrameView::performPostLayoutTasks()
 
 bool FrameView::wasViewportResized()
 {
-    ASSERT(m_frame);
+    DCHECK(m_frame);
     LayoutViewItem layoutViewItem = this->layoutViewItem();
     if (layoutViewItem.isNull())
         return false;
-    ASSERT(layoutViewItem.style());
+    DCHECK(layoutViewItem.style());
     return (layoutSize(IncludeScrollbars) != m_lastViewportSize || layoutViewItem.style()->zoom() != m_lastZoomFactor);
 }
 
 void FrameView::sendResizeEventIfNeeded()
 {
-    ASSERT(m_frame);
+    DCHECK(m_frame);
 
     LayoutViewItem layoutViewItem = this->layoutViewItem();
     if (layoutViewItem.isNull() || layoutViewItem.document().printing())
@@ -2188,7 +2190,7 @@ void FrameView::updateCounters()
 
 IntRect FrameView::windowClipRect(IncludeScrollbarsInRect scrollbarInclusion) const
 {
-    ASSERT(m_frame->view() == this);
+    DCHECK(m_frame->view() == this);
 
     LayoutRect clipRect(LayoutPoint(), LayoutSize(visibleContentSize(scrollbarInclusion)));
     layoutViewItem().mapToVisualRectInAncestorSpace(&layoutView()->containerForPaintInvalidation(), clipRect);
@@ -2197,7 +2199,10 @@ IntRect FrameView::windowClipRect(IncludeScrollbarsInRect scrollbarInclusion) co
 
 bool FrameView::shouldUseIntegerScrollOffset() const
 {
-    if (m_frame->settings() && !m_frame->settings()->preferCompositingToLCDTextEnabled())
+    LayoutViewItem layoutView = this->layoutViewItem();

[chrishtr, 2016/07/27 19:26:00]

Ditto.

I think you should just write:

 if (m_frame->settings() &&
(!m_frame->settings()->preferCompositingToLCDTextEnabled() ||
RuntimeEnabledFeatures::compositeOpaqueScrollersEnabled()))

[Stephen Chennney, 2016/07/28 13:55:38]

We don't need anything at all. The logic works such that we can only be trying
to use high DPI when the preferCompositingToLCDTextEnabled is false, so the
existing check catches it.

+    if (layoutView.isNull())
+        return false;
+    if (layoutView.layer()->needsCompositedScrolling())
         return true;
 
     return ScrollableArea::shouldUseIntegerScrollOffset();
@@ -2604,7 +2609,7 @@ void FrameView::updatePaintProperties()
 {
     TRACE_EVENT0("blink", "FrameView::updatePaintProperties");
 
-    ASSERT(RuntimeEnabledFeatures::slimmingPaintV2Enabled());
+    DCHECK(RuntimeEnabledFeatures::slimmingPaintV2Enabled());
 
     forAllNonThrottledFrameViews([](FrameView& frameView) { frameView.lifecycle().advanceTo(DocumentLifecycle::InPrePaint); });
     PrePaintTreeWalk().walk(*this);
@@ -2616,10 +2621,10 @@ void FrameView::synchronizedPaint()
     TRACE_EVENT0("blink", "FrameView::synchronizedPaint");
     SCOPED_BLINK_UMA_HISTOGRAM_TIMER("Blink.Paint.UpdateTime");
 
-    ASSERT(frame() == page()->mainFrame() || (!frame().tree().parent()->isLocalFrame()));
+    DCHECK(frame() == page()->mainFrame() || (!frame().tree().parent()->isLocalFrame()));
 
     LayoutViewItem view = layoutViewItem();
-    ASSERT(!view.isNull());
+    DCHECK(!view.isNull());
     forAllNonThrottledFrameViews([](FrameView& frameView) { frameView.lifecycle().advanceTo(DocumentLifecycle::InPaint); });
 
     // A null graphics layer can occur for painting of SVG images that are not parented into the main frame tree,
@@ -2668,14 +2673,14 @@ void FrameView::pushPaintArtifactToCompositor()
 {
     TRACE_EVENT0("blink", "FrameView::pushPaintArtifactToCompositor");
 
-    ASSERT(RuntimeEnabledFeatures::slimmingPaintV2Enabled());
+    DCHECK(RuntimeEnabledFeatures::slimmingPaintV2Enabled());
 
     LayoutViewItem viewItem = layoutViewItem();
-    ASSERT(!viewItem.isNull());
+    DCHECK(!viewItem.isNull());
 
     // TODO(jbroman): Simplify the path to PaintController.
     PaintLayer* layer = viewItem.layer();
-    ASSERT(layer);
+    DCHECK(layer);
     if (!layer->hasCompositedLayerMapping())
         return;
     GraphicsLayer* rootGraphicsLayer = layer->compositedLayerMapping()->mainGraphicsLayer();
@@ -2761,7 +2766,7 @@ void FrameView::updateStyleAndLayoutIfNeededRecursiveInternal()
 
     // These asserts ensure that parent frames are clean, when child frames finished updating layout and style.
     checkDoesNotNeedLayout();
-    ASSERT(!m_frame->document()->hasSVGFilterElementsRequiringLayerUpdate());
+    DCHECK(!m_frame->document()->hasSVGFilterElementsRequiringLayerUpdate());
 #if ENABLE(ASSERT)
     m_frame->document()->layoutView()->assertLaidOut();
 #endif
@@ -3090,7 +3095,7 @@ void FrameView::removeResizerArea(LayoutBox& resizerBox)
 
 void FrameView::addScrollableArea(ScrollableArea* scrollableArea)
 {
-    ASSERT(scrollableArea);
+    DCHECK(scrollableArea);
     if (!m_scrollableAreas)
         m_scrollableAreas = new ScrollableAreaSet;
     m_scrollableAreas->add(scrollableArea);
@@ -3111,7 +3116,7 @@ void FrameView::removeScrollableArea(ScrollableArea* scrollableArea)
 
 void FrameView::addAnimatingScrollableArea(ScrollableArea* scrollableArea)
 {
-    ASSERT(scrollableArea);
+    DCHECK(scrollableArea);
     if (!m_animatingScrollableAreas)
         m_animatingScrollableAreas = new ScrollableAreaSet;
     m_animatingScrollableAreas->add(scrollableArea);
@@ -3143,7 +3148,7 @@ void FrameView::setParent(Widget* parentView)
 
 void FrameView::removeChild(Widget* child)
 {
-    ASSERT(child->parent() == this);
+    DCHECK(child->parent() == this);
 
     if (child->isFrameView())
         removeScrollableArea(toFrameView(child));
@@ -3214,7 +3219,7 @@ IntPoint FrameView::maximumScrollPosition() const
 
 void FrameView::addChild(Widget* child)
 {
-    ASSERT(child != this && !child->parent());
+    DCHECK(child != this && !child->parent());
     child->setParent(this);
     m_children.add(child);
 }
@@ -3370,7 +3375,7 @@ void FrameView::setScrollOffset(const DoublePoint& offset, ScrollType scrollType
 
     if (m_frame->settings() && m_frame->settings()->rootLayerScrolls()) {
         // Don't scroll the FrameView!
-        ASSERT_NOT_REACHED();
+        NOTREACHED();
     }
 
     m_scrollPosition = newPosition;
@@ -3545,7 +3550,7 @@ IntRect FrameView::adjustScrollbarRectForResizer(const IntRect& rect, Scrollbar&
 
 bool FrameView::adjustScrollbarExistence(ComputeScrollbarExistenceOption option)
 {
-    ASSERT(m_inUpdateScrollbars);
+    DCHECK(m_inUpdateScrollbars);
 
     // If we came in here with the view already needing a layout, then go ahead and do that
     // first.  (This will be the common case, e.g., when the page changes due to window resizing for example).
@@ -4146,7 +4151,7 @@ void FrameView::updateViewportIntersectionIfNeeded()
         m_viewportIntersection = frameRect();
         return;
     }
-    ASSERT(!parent->m_needsUpdateViewportIntersection);
+    DCHECK(!parent->m_needsUpdateViewportIntersection);
 
     // If our parent is hidden, then we are too.
     if (parent->m_viewportIntersection.isEmpty()) {
@@ -4159,7 +4164,7 @@ void FrameView::updateViewportIntersectionIfNeeded()
     // parent is throttled, we'll use possible stale layout information and
     // rely on the fact that another lifecycle update will be scheduled once
     // our parent becomes unthrottled.
-    ASSERT(parent->lifecycle().state() >= DocumentLifecycle::LayoutClean || parent->shouldThrottleRendering());
+    DCHECK(parent->lifecycle().state() >= DocumentLifecycle::LayoutClean || parent->shouldThrottleRendering());
     m_viewportIntersection = parent->contentsToRootFrame(frameRect());
 
     // TODO(skyostil): Expand the viewport to make it less likely to see stale content while scrolling.