Use intersection observer to control frame throttling

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

 /*
    Copyright (C) 1997 Martin Jones (mjones@kde.org)
              (C) 1998 Waldo Bastian (bastian@kde.org)
              (C) 1998, 1999 Torben Weis (weis@kde.org)
              (C) 1999 Lars Knoll (knoll@kde.org)
              (C) 1999 Antti Koivisto (koivisto@kde.org)
    Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009 Apple Inc. All rights reserved.
 
    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Library General Public
    License as published by the Free Software Foundation; either
    version 2 of the License, or (at your option) any later version.
 
    This library is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
    Library General Public License for more details.
 
    You should have received a copy of the GNU Library General Public License
    along with this library; see the file COPYING.LIB.  If not, write to
    the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
    Boston, MA 02110-1301, USA.
 */
 
 #ifndef FrameView_h
 #define FrameView_h
 
 #include "core/CoreExport.h"
 #include "core/dom/DocumentLifecycle.h"
+#include "core/dom/IntersectionObserverCallback.h"
 #include "core/frame/FrameViewAutoSizeInfo.h"
 #include "core/frame/LayoutSubtreeRootList.h"
 #include "core/frame/RootFrameViewport.h"
 #include "core/layout/ScrollAnchor.h"
 #include "core/layout/api/LayoutViewItem.h"
 #include "core/paint/FirstMeaningfulPaintDetector.h"
 #include "core/paint/PaintInvalidationCapableScrollableArea.h"
 #include "core/paint/PaintPhase.h"
 #include "platform/RuntimeEnabledFeatures.h"
 #include "platform/Widget.h"
@@ skipping 544 matching lines @@
 
     LayoutAnalyzer* layoutAnalyzer() { return m_analyzer.get(); }
 
     // Returns true if this frame should not render or schedule visual updates.
     bool shouldThrottleRendering() const;
 
     // Returns true if this frame could potentially skip rendering and avoid
     // scheduling visual updates.
     bool canThrottleRendering() const;
     bool isHiddenForThrottling() const { return m_hiddenForThrottling; }
+    void setupRenderThrottling();
 
     // For testing, run pending intersection observer notifications for this frame.
-    void notifyRenderThrottlingObserversForTesting();
+    void updateRenderThrottlingStatusForTesting();
 
     // Paint properties for SPv2 Only.
     void setPreTranslation(PassRefPtr<TransformPaintPropertyNode> preTranslation) { m_preTranslation = preTranslation; }
     TransformPaintPropertyNode* preTranslation() const { return m_preTranslation.get(); }
 
     void setScrollTranslation(PassRefPtr<TransformPaintPropertyNode> scrollTranslation) { m_scrollTranslation = scrollTranslation; }
     TransformPaintPropertyNode* scrollTranslation() const { return m_scrollTranslation.get(); }
 
     void setContentClip(PassRefPtr<ClipPaintPropertyNode> contentClip) { m_contentClip = contentClip; }
     ClipPaintPropertyNode* contentClip() const { return m_contentClip.get(); }
@@ skipping 54 matching lines @@
             : m_scope(&view->m_inUpdateScrollbars, true)
         { }
     private:
         AutoReset<bool> m_scope;
     };
 
     // Only for LayoutPart to traverse into sub frames during paint invalidation.
     void invalidateTreeIfNeeded(const PaintInvalidationState&);
 
 private:
+    class IntersectionObserverCallback : public blink::IntersectionObserverCallback {
+    public:
+        IntersectionObserverCallback(FrameView*);
+
+        // IntersectionObserverCallback implementation:
+        void handleEvent(const HeapVector<Member<IntersectionObserverEntry>>&, IntersectionObserver&) override;
+        ExecutionContext* getExecutionContext() const override;
+
+        DECLARE_TRACE();
+
+    private:
+        Member<FrameView> m_frameView;

[szager1, 2016/08/30 23:57:12]

I think this should be WeakMember, to avoid a reference cycle:

FrameView->IntersectionObserver->IntersectionObserverCallback->FrameView.

[Sami, 2016/08/31 11:08:56]

I guess I was thinking that with Oilpan in-heap reference cycles aren't an issue
anymore, but maybe a WeakMember is still more appropriate? Done.

+    };
+
     explicit FrameView(LocalFrame*);
 
     void setScrollOffset(const DoublePoint&, ScrollType) override;
 
     void updateLifecyclePhasesInternal(DocumentLifecycle::LifecycleState targetState);
 
     void invalidateTreeIfNeededRecursive();
     void scrollContentsIfNeededRecursive();
     void updateStyleAndLayoutIfNeededRecursive();
     void updatePaintProperties();
@@ skipping 90 matching lines @@
 
     // LayoutObject for the viewport-defining element (see Document::viewportDefiningElement).
     LayoutObject* viewportLayoutObject() const;
 
     void collectAnnotatedRegions(LayoutObject&, Vector<AnnotatedRegionValue>&) const;
 
     template <typename Function> void forAllNonThrottledFrameViews(const Function&);
 
     void setNeedsUpdateViewportIntersection();
     void updateViewportIntersectionsForSubtree(DocumentLifecycle::LifecycleState targetState);
-    void updateViewportIntersectionIfNeeded();
-    void notifyRenderThrottlingObservers();
-    void updateThrottlingStatus();
+    void updateRenderThrottlingStatus(bool hidden, bool subtreeThrottled);
     void notifyResizeObservers();
 
     // PaintInvalidationCapableScrollableArea
     LayoutScrollbarPart* resizer() const override { return nullptr; }
 
     bool checkLayoutInvalidationIsAllowed() const;
 
     LayoutSize m_size;
 
     typedef HashSet<RefPtr<LayoutEmbeddedObject>> EmbeddedObjectSet;
@@ skipping 18 matching lines @@
     bool m_hasPendingLayout;
     LayoutSubtreeRootList m_layoutSubtreeRootList;
     DepthOrderedLayoutObjectList m_orthogonalWritingModeRootList;
 
     bool m_layoutSchedulingEnabled;
     bool m_inSynchronousPostLayout;
     int m_layoutCount;
     unsigned m_nestedLayoutCount;
     Timer<FrameView> m_postLayoutTasksTimer;
     Timer<FrameView> m_updateWidgetsTimer;
-    std::unique_ptr<CancellableTaskFactory> m_renderThrottlingObserverNotificationFactory;
 
     bool m_firstLayout;
     bool m_isTransparent;
     Color m_baseBackgroundColor;
     IntSize m_lastViewportSize;
     float m_lastZoomFactor;
 
     AtomicString m_mediaType;
     AtomicString m_mediaTypeWhenNotPrinting;
 
@@ skipping 61 matching lines @@
 
     // Mark if something has changed in the mapping from Frame to GraphicsLayer
     // and the Frame Timing regions should be recalculated.
     bool m_frameTimingRequestsDirty;
 
     // Exists only on root frame.
     // TODO(bokan): crbug.com/484188. We should specialize FrameView for the
     // main frame.
     Member<RootFrameViewport> m_viewportScrollableArea;
 
-    // This frame's bounds in the root frame's content coordinates, clipped
-    // recursively through every ancestor view.
-    IntRect m_viewportIntersection;
-    bool m_viewportIntersectionValid;
-
     // The following members control rendering pipeline throttling for this
     // frame. They are only updated in response to intersection observer
     // notifications, i.e., not in the middle of the lifecycle.
     bool m_hiddenForThrottling;
-    bool m_crossOriginForThrottling;
     bool m_subtreeThrottled;
 
     // Paint properties for SPv2 Only.
     // The hierarchy of transform subtree created by a FrameView.
     // [ preTranslation ]               The offset from Widget::frameRect. Establishes viewport.
     //     +---[ scrollTranslation ]    Frame scrolling.
     // TODO(trchen): These will not be needed once settings->rootLayerScrolls() is enabled.
     RefPtr<TransformPaintPropertyNode> m_preTranslation;
     RefPtr<TransformPaintPropertyNode> m_scrollTranslation;
     // The content clip clips the document (= LayoutView) but not the scrollbars.
     // TODO(trchen): This will not be needed once settings->rootLayerScrolls() is enabled.
     RefPtr<ClipPaintPropertyNode> m_contentClip;
 
     // These nodes represent the root nodes of each property tree.
     // Only the root frame should create them and they will be no-op.
     RefPtr<TransformPaintPropertyNode> m_rootTransform;
     RefPtr<ClipPaintPropertyNode> m_rootClip;
     RefPtr<EffectPaintPropertyNode> m_rootEffect;
 
     // This is set on the local root frame view only.
     DocumentLifecycle::LifecycleState m_currentUpdateLifecyclePhasesTargetState;
 
     ScrollAnchor m_scrollAnchor;
 
     bool m_needsScrollbarsUpdate;
     bool m_suppressAdjustViewSize;
     bool m_allowsLayoutInvalidationAfterLayoutClean;
 
+    Member<IntersectionObserver> m_intersectionObserver;
+
     // For testing.
     struct ObjectPaintInvalidation {
         String name;
         PaintInvalidationReason reason;
     };
     std::unique_ptr<Vector<ObjectPaintInvalidation>> m_trackedObjectPaintInvalidations;
 };
 
 inline void FrameView::incrementVisuallyNonEmptyCharacterCount(unsigned count)
 {
@@ skipping 17 matching lines @@
     if (m_visuallyNonEmptyPixelCount > visualPixelThreshold)
         setIsVisuallyNonEmpty();
 }
 
 DEFINE_TYPE_CASTS(FrameView, Widget, widget, widget->isFrameView(), widget.isFrameView());
 DEFINE_TYPE_CASTS(FrameView, ScrollableArea, scrollableArea, scrollableArea->isFrameView(), scrollableArea.isFrameView());
 
 } // namespace blink
 
 #endif // FrameView_h