FrameView: Remove redundant tree walk when unthrottling display:none frames

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

 /*
  * Copyright (C) 1998, 1999 Torben Weis <weis@kde.org>
  *                     1999 Lars Knoll <knoll@kde.org>
  *                     1999 Antti Koivisto <koivisto@kde.org>
  *                     2000 Dirk Mueller <mueller@kde.org>
  * Copyright (C) 2004, 2005, 2006, 2007, 2008 Apple Inc. All rights reserved.
  *           (C) 2006 Graham Dennis (graham.dennis@gmail.com)
  *           (C) 2006 Alexey Proskuryakov (ap@nypop.com)
  * Copyright (C) 2009 Google Inc. All rights reserved.
  *
@@ skipping 4722 matching lines @@
   if (targetState == DocumentLifecycle::PaintClean &&
       frame().document()->intersectionObserverController())
     frame()
         .document()
         ->intersectionObserverController()
         ->computeTrackedIntersectionObservations();
 
   // Don't throttle display:none frames (see updateRenderThrottlingStatus).
   HTMLFrameOwnerElement* ownerElement = m_frame->deprecatedLocalOwner();
   if (m_hiddenForThrottling && ownerElement && !ownerElement->layoutObject()) {
-    updateRenderThrottlingStatus(m_hiddenForThrottling, m_subtreeThrottled);
+    // No need to notify children because descendants of display:none frames
+    // should remain throttled.
+    updateRenderThrottlingStatus(m_hiddenForThrottling, m_subtreeThrottled,
+                                 DontForceThrottlingInvalidation,
+                                 DontNotifyChildren);
     DCHECK(!canThrottleRendering());
   }
 
   for (Frame* child = m_frame->tree().firstChild(); child;
        child = child->tree().nextSibling()) {
     if (!child->isLocalFrame())
       continue;
     if (FrameView* view = toLocalFrame(child)->view())
       view->updateViewportIntersectionsForSubtree(targetState);
   }
 }
 
 void FrameView::updateRenderThrottlingStatusForTesting() {
   m_visibilityObserver->deliverObservationsForTesting();
 }
 
 void FrameView::crossOriginStatusChanged() {
   // Cross-domain status is not stored as a dirty bit within FrameView,
   // so force-invalidate throttling status when it changes regardless of
   // previous or new value.
-  updateRenderThrottlingStatus(m_hiddenForThrottling, m_subtreeThrottled, true);
+  updateRenderThrottlingStatus(m_hiddenForThrottling, m_subtreeThrottled,
+                               ForceThrottlingInvalidation);
 }
 
-void FrameView::updateRenderThrottlingStatus(bool hidden,
-                                             bool subtreeThrottled,
-                                             bool forceThrottlingInvalidation) {
+void FrameView::updateRenderThrottlingStatus(
+    bool hidden,
+    bool subtreeThrottled,
+    ForceThrottlingInvalidationBehavior forceThrottlingInvalidationBehavior,
+    NotifyChildrenBehavior notifyChildrenBehavior) {
   TRACE_EVENT0("blink", "FrameView::updateRenderThrottlingStatus");
   DCHECK(!isInPerformLayout());
   DCHECK(!m_frame->document() || !m_frame->document()->inStyleRecalc());
   bool wasThrottled = canThrottleRendering();
 
   // Note that we disallow throttling of 0x0 and display:none frames because
   // some sites use them to drive UI logic.
   HTMLFrameOwnerElement* ownerElement = m_frame->deprecatedLocalOwner();
   m_hiddenForThrottling = hidden && !frameRect().isEmpty() &&
                           (ownerElement && ownerElement->layoutObject());
   m_subtreeThrottled = subtreeThrottled;
 
   bool isThrottled = canThrottleRendering();
   bool becameUnthrottled = wasThrottled && !isThrottled;
 
   // If this FrameView became unthrottled or throttled, we must make sure all
   // its children are notified synchronously. Otherwise we 1) might attempt to
   // paint one of the children with an out-of-date layout before
   // |updateRenderThrottlingStatus| has made it throttled or 2) fail to
   // unthrottle a child whose parent is unthrottled by a later notification.
-  if (wasThrottled != isThrottled || forceThrottlingInvalidation) {
+  if (notifyChildrenBehavior == NotifyChildren &&
+      (wasThrottled != isThrottled ||
+       forceThrottlingInvalidationBehavior == ForceThrottlingInvalidation)) {
     for (const Member<Widget>& child : *children()) {
       if (child->isFrameView()) {
         FrameView* childView = toFrameView(child);
         childView->updateRenderThrottlingStatus(
             childView->m_hiddenForThrottling, isThrottled);
       }
     }
   }
 
   ScrollingCoordinator* scrollingCoordinator = this->scrollingCoordinator();
-  if (becameUnthrottled || forceThrottlingInvalidation) {
+  if (becameUnthrottled ||
+      forceThrottlingInvalidationBehavior == ForceThrottlingInvalidation) {
     // ScrollingCoordinator needs to update according to the new throttling
     // status.
     if (scrollingCoordinator)
       scrollingCoordinator->notifyGeometryChanged();
     // Start ticking animation frames again if necessary.
     if (page())
       page()->animator().scheduleVisualUpdate(m_frame.get());
     // Force a full repaint of this frame to ensure we are not left with a
     // partially painted version of this frame's contents if we skipped
     // painting them while the frame was throttled.
@@ skipping 373 matching lines @@
 void FrameView::setAnimationHost(
     std::unique_ptr<CompositorAnimationHost> host) {
   m_animationHost = std::move(host);
 }
 
 LayoutUnit FrameView::caretWidth() const {
   return LayoutUnit(getHostWindow()->windowToViewportScalar(1));
 }
 
 }  // namespace blink