Make Blink stop scheduling its own Layout, and use the compositor's timer instead

Source/core/page/FrameView.cpp

Index: Source/core/page/FrameView.cpp
diff --git a/Source/core/page/FrameView.cpp b/Source/core/page/FrameView.cpp
index 15389b0e919cce3bce83e0cdb1651a9223c04154..061fb96189efb2928a1d49923e90f5b519b4fbea 100644
--- a/Source/core/page/FrameView.cpp
+++ b/Source/core/page/FrameView.cpp
@@ -155,7 +155,7 @@ FrameView::FrameView(Frame* frame)
     : m_frame(frame)
     , m_canHaveScrollbars(true)
     , m_slowRepaintObjectCount(0)
-    , m_layoutTimer(this, &FrameView::layoutTimerFired)
+    , m_layoutIsScheduledWithEmbedder(false)
     , m_layoutRoot(0)
     , m_inSynchronousPostLayout(false)
     , m_postLayoutTasksTimer(this, &FrameView::postLayoutTimerFired)
@@ -247,7 +247,7 @@ void FrameView::reset()
     m_contentIsOpaque = false;
     m_borderX = 30;
     m_borderY = 30;
-    m_layoutTimer.stop();
+    unscheduleRelayout();
     m_layoutRoot = 0;
     m_delayedLayout = false;
     m_doFullRepaint = true;
@@ -691,7 +691,7 @@ void FrameView::updateCompositingLayersAfterStyleChange()
         return;
 
     // If we expect to update compositing after an incipient layout, don't do so here.
-    if (m_doingPreLayoutStyleUpdate || layoutPending() || renderView->needsLayout())
+    if (m_doingPreLayoutStyleUpdate || layoutIsScheduledWithEmbedder() || renderView->needsLayout())
         return;
 
     // This call will make sure the cached hasAcceleratedCompositing is updated from the pref
@@ -816,7 +816,7 @@ bool FrameView::isSoftwareRenderable() const
 
 RenderObject* FrameView::layoutRoot(bool onlyDuringLayout) const
 {
-    return onlyDuringLayout && layoutPending() ? 0 : m_layoutRoot;
+    return onlyDuringLayout && layoutIsScheduledWithEmbedder() ? 0 : m_layoutRoot;
 }
 
 static inline void collectFrameViewChildren(FrameView* frameView, Vector<RefPtr<FrameView> >& frameViews)
@@ -882,7 +882,7 @@ void FrameView::layout(bool allowSubtree)
     // Every scroll that happens during layout is programmatic.
     TemporaryChange<bool> changeInProgrammaticScroll(m_inProgrammaticScroll, true);
 
-    m_layoutTimer.stop();
+    unscheduleRelayout();
     m_delayedLayout = false;
     m_setNeedsLayoutWasDeferred = false;
 
@@ -1875,6 +1875,13 @@ void FrameView::layoutTimerFired(Timer<FrameView>*)
     layout();
 }
 
+void FrameView::scheduleLayoutWithEmbedder()
+{
+    // FIXME: Right now we're hijacking the scheduleAnimation codepath.
+    scheduleAnimation();
+    m_layoutIsScheduledWithEmbedder = true;
+}
+
 void FrameView::scheduleRelayout()
 {
     ASSERT(m_frame->view() == this);
@@ -1896,14 +1903,7 @@ void FrameView::scheduleRelayout()
     if (m_frame->ownerRenderer() && frame()->document()->shouldDisplaySeamlesslyWithParent())
         m_frame->ownerRenderer()->setNeedsLayout(true, MarkContainingBlockChain);
 
-    int delay = m_frame->document()->minimumLayoutDelay();
-    if (m_layoutTimer.isActive() && m_delayedLayout && !delay)
-        unscheduleRelayout();
-    if (m_layoutTimer.isActive())
-        return;
-
-    m_delayedLayout = delay != 0;
-    m_layoutTimer.startOneShot(delay * 0.001);
+    scheduleLayoutWithEmbedder();
 }
 
 static bool isObjectAncestorContainerOf(RenderObject* ancestor, RenderObject* descendant)
@@ -1926,7 +1926,7 @@ void FrameView::scheduleRelayoutOfSubtree(RenderObject* relayoutRoot)
         return;
     }
 
-    if (layoutPending() || !m_layoutSchedulingEnabled) {
+    if (layoutIsScheduledWithEmbedder() || !m_layoutSchedulingEnabled) {
         if (m_layoutRoot != relayoutRoot) {
             if (isObjectAncestorContainerOf(m_layoutRoot, relayoutRoot)) {
                 // Keep the current root
@@ -1952,14 +1952,13 @@ void FrameView::scheduleRelayoutOfSubtree(RenderObject* relayoutRoot)
         m_layoutRoot = relayoutRoot;
         ASSERT(!m_layoutRoot->container() || !m_layoutRoot->container()->needsLayout());
         InspectorInstrumentation::didInvalidateLayout(m_frame.get());
-        m_delayedLayout = delay != 0;
-        m_layoutTimer.startOneShot(delay * 0.001);
+        scheduleLayoutWithEmbedder();
     }
 }
 
-bool FrameView::layoutPending() const
+bool FrameView::layoutIsScheduledWithEmbedder() const
 {
-    return m_layoutTimer.isActive();
+    return m_layoutIsScheduledWithEmbedder;
 }
 
 bool FrameView::needsLayout() const
@@ -1971,7 +1970,7 @@ bool FrameView::needsLayout() const
         return false;
 
     RenderView* renderView = this->renderView();
-    return layoutPending()
+    return layoutIsScheduledWithEmbedder()
         || (renderView && renderView->needsLayout())
         || m_layoutRoot
         || (m_deferSetNeedsLayouts && m_setNeedsLayoutWasDeferred);
@@ -1990,15 +1989,15 @@ void FrameView::setNeedsLayout()
 
 void FrameView::unscheduleRelayout()
 {
-    if (!m_layoutTimer.isActive())
-        return;
-
-    m_layoutTimer.stop();
-    m_delayedLayout = false;
+    // FIXME: We should just remove this method.
+    m_layoutIsScheduledWithEmbedder = false;
 }
 
 void FrameView::serviceScriptedAnimations(double monotonicAnimationStartTime)
 {
+    // The Animation timer is also used for scheduling layouts.
+    updateLayoutAndStyleIfNeededRecursive();
+
     for (RefPtr<Frame> frame = m_frame; frame; frame = frame->tree()->traverseNext()) {
         frame->view()->serviceScrollAnimations();
         if (!RuntimeEnabledFeatures::webAnimationsCSSEnabled())
@@ -2987,6 +2986,7 @@ void FrameView::updateLayoutAndStyleIfNeededRecursive()
 
     m_frame->document()->updateStyleIfNeeded();
 
+    unscheduleRelayout();
     if (needsLayout())
         layout();