Deferred frame loading stats v2

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 4327 matching lines @@
     parent->m_needsUpdateViewportIntersectionInSubtree = true;
 }
 
 void FrameView::updateViewportIntersectionIfNeeded() {
   if (!m_needsUpdateViewportIntersection)
     return;
   m_needsUpdateViewportIntersection = false;
   m_viewportIntersectionValid = true;
   FrameView* parent = parentFrameView();
   if (!parent) {
+    // display:none frames have no parent because they're not in the DOM.

[dcheng, 2016/10/07 05:52:40]

I don't understand this comment in conjunction with the code below. I believe
what happens with display:none iframes is they end up attached to the frame tree
(this can be tested by appending a style="display:none" iframe to the DOM and
observing that window.lenght) increases). However, it's not in the layout tree
(see below)

+    if (HTMLFrameOwnerElement* element = frame().deprecatedLocalOwner()) {
+      if (const ComputedStyle* style = element->computedStyle()) {

[dgrogan, 2016/10/05 01:19:08]

I'm trying to detect when an iframe has style="display:none". But
element->computedStyle() always returns nullptr. Any ideas how I can access the
style from here? (It's also probably not a good sign that I'm using deprecated
stuff.)

[dcheng, 2016/10/07 05:52:40]

I think what's happening here is that there's no LayoutObject, so ComputedStyle
will always be null.

Maybe not having a LayoutObject is a good enough proxy for display:none? +timloh
who knows much more about CSS than me.

+        if (style->display() == EDisplay::None)
+          frame().document()->wouldLoadBecause(WouldLoadDisplayNone);
+      }
+    }
+    frame().document()->wouldLoadBecause(WouldLoadOutOfProcess);
     m_viewportIntersection = frameRect();
     return;
   }
   ASSERT(!parent->m_needsUpdateViewportIntersection);
 
+  bool parentLoaded = parent->frame().document()->wouldLoadReason() != Created;
+  if (parentLoaded) {
+    if (frameRect().isEmpty()) {
+      frame().document()->wouldLoadBecause(WouldLoadZeroByZero);
+    } else if (frameRect().maxY() < 0) {
+      frame().document()->wouldLoadBecause(WouldLoadAbove);
+    } else if (frameRect().maxX() < 0) {
+      frame().document()->wouldLoadBecause(WouldLoadLeft);
+    }
+  }
+
   // If our parent is hidden, then we are too.
   if (parent->m_viewportIntersection.isEmpty()) {
     m_viewportIntersection = parent->m_viewportIntersection;
     return;
   }
 
   // Transform our bounds into the root frame's content coordinate space,
   // making sure we have valid layout data in our parent document. If our
   // 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());
   m_viewportIntersection = parent->contentsToRootFrame(frameRect());
 
   // TODO(skyostil): Expand the viewport to make it less likely to see stale content while scrolling.
   IntRect viewport = parent->m_viewportIntersection;
   m_viewportIntersection.intersect(viewport);
+
+  if (parentLoaded && !m_viewportIntersection.isEmpty())
+    frame().document()->wouldLoadBecause(WouldLoadVisible);
 }
 
 void FrameView::updateViewportIntersectionsForSubtree(
     DocumentLifecycle::LifecycleState targetState) {
   bool hadValidIntersection = m_viewportIntersectionValid;
   bool hadEmptyIntersection = m_viewportIntersection.isEmpty();
   updateViewportIntersectionIfNeeded();
 
   // Notify javascript IntersectionObservers
   if (targetState == DocumentLifecycle::PaintClean &&
@@ skipping 65 matching lines @@
 
 void FrameView::notifyRenderThrottlingObservers() {
   TRACE_EVENT0("blink", "FrameView::notifyRenderThrottlingObservers");
   DCHECK(!isInPerformLayout());
   DCHECK(frame().document());
   DCHECK(!frame().document()->inStyleRecalc());
   bool wasThrottled = canThrottleRendering();
 
   updateThrottlingStatus();
 
-  frame().document()->onVisibilityMaybeChanged(!m_hiddenForThrottling);
-
   bool becameThrottled = !wasThrottled && canThrottleRendering();
   bool becameUnthrottled = wasThrottled && !canThrottleRendering();
   ScrollingCoordinator* scrollingCoordinator = this->scrollingCoordinator();
   if (becameThrottled) {
     // If this FrameView became throttled, we must make sure all of its
     // children become throttled at the same time. Otherwise we might
     // attempt to paint one of the children with an out-of-date layout
     // before |notifyRenderThrottlingObservers| has made it throttled.
     forAllNonThrottledFrameViews([](FrameView& frameView) {
       frameView.m_subtreeThrottled = true;
@@ skipping 37 matching lines @@
 }
 
 bool FrameView::canThrottleRendering() const {
   if (!RuntimeEnabledFeatures::renderingPipelineThrottlingEnabled())
     return false;
   return m_subtreeThrottled ||
          (m_hiddenForThrottling && m_crossOriginForThrottling);
 }
 
 }  // namespace blink