Turn on render throttling for iframes with pending sheets.

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 162 matching lines @@
 #endif
       m_horizontalScrollbarMode(ScrollbarAuto),
       m_verticalScrollbarMode(ScrollbarAuto),
       m_horizontalScrollbarLock(false),
       m_verticalScrollbarLock(false),
       m_scrollbarsSuppressed(false),
       m_inUpdateScrollbars(false),
       m_frameTimingRequestsDirty(true),
       m_hiddenForThrottling(false),
       m_subtreeThrottled(false),
+      m_lifecycleUpdatesThrottled(false),
       m_currentUpdateLifecyclePhasesTargetState(
           DocumentLifecycle::Uninitialized),
       m_scrollAnchor(this),
       m_scrollbarManager(*this),
       m_needsScrollbarsUpdate(false),
       m_suppressAdjustViewSize(false),
       m_allowsLayoutInvalidationAfterLayoutClean(true) {
   ASSERT(m_frame);
   init();
 }
@@ skipping 27 matching lines @@
   visitor->trace(m_viewportScrollableArea);
   visitor->trace(m_visibilityObserver);
   visitor->trace(m_scrollAnchor);
   visitor->trace(m_anchoringAdjustmentQueue);
   visitor->trace(m_scrollbarManager);
   Widget::trace(visitor);
   ScrollableArea::trace(visitor);
 }
 
 void FrameView::reset() {
+  // The compositor throttles the main frame using deferred commits, we can't
+  // throttle it here or it seems the root compositor doesn't get setup
+  // properly.
+  if (RuntimeEnabledFeatures::
+          renderingPipelineThrottlingLoadingIframesEnabled())
+    m_lifecycleUpdatesThrottled = !frame().isMainFrame();
   m_hasPendingLayout = false;
   m_layoutSchedulingEnabled = true;
   m_inSynchronousPostLayout = false;
   m_layoutCount = 0;
   m_nestedLayoutCount = 0;
   m_postLayoutTasksTimer.stop();
   m_updateWidgetsTimer.stop();
   m_firstLayout = true;
   m_safeToPropagateScrollToParent = true;
   m_lastViewportSize = IntSize();
@@ skipping 51 matching lines @@
   // frames whose owner element is remote.
   Element* targetElement = frame().deprecatedLocalOwner();
   if (!targetElement)
     return;
 
   m_visibilityObserver = new ElementVisibilityObserver(
       targetElement, WTF::bind(
                          [](FrameView* frameView, bool isVisible) {
                            frameView->updateRenderThrottlingStatus(
                                !isVisible, frameView->m_subtreeThrottled);
+                           frameView->maybeRecordLoadReason();
                          },
                          wrapWeakPersistent(this)));
   m_visibilityObserver->start();
 }
 
 void FrameView::dispose() {
   RELEASE_ASSERT(!isInPerformLayout());
 
   if (ScrollAnimatorBase* scrollAnimator = existingScrollAnimator())
     scrollAnimator->cancelAnimation();
@@ skipping 4122 matching lines @@
       layoutViewItem.invalidatePaintForViewAndCompositedLayers();
   }
 
   bool hasHandlers = m_frame->host() &&
                      m_frame->host()->eventHandlerRegistry().hasEventHandlers(
                          EventHandlerRegistry::TouchStartOrMoveEventBlocking);
   if (wasThrottled != canThrottleRendering() && scrollingCoordinator &&
       hasHandlers)
     scrollingCoordinator->touchEventTargetRectsDidChange();
 
+#if DCHECK_IS_ON()
+  // Make sure we never have an unthrottled frame inside a throttled one.
+  FrameView* parent = parentFrameView();
+  while (parent) {
+    DCHECK(canThrottleRendering() || !parent->canThrottleRendering());
+    parent = parent->parentFrameView();
+  }
+#endif
+}
+
+void FrameView::maybeRecordLoadReason() {

[ojan, 2016/11/08 21:27:06]

Nit: I have a pet peeve around putting "maybe" in method names. I think it
provides less value than the cost of making the code hard to read. But, just my
opinion, so feel free to ignore.

[esprehn, 2016/11/08 22:18:35]

Yeah... the code this is calling is already called maybeRecordLoadReason, so I'd
rather keep these two consistent since this is just a wrapper around the other
one. You reviewed the other one too :P We should probably just rename them both.

I added a TODO to rename them to recordDeferredLoadReason.

   FrameView* parent = parentFrameView();
   if (frame().document()->frame()) {
     if (!parent) {
       HTMLFrameOwnerElement* element = frame().deprecatedLocalOwner();
       if (!element)
         frame().document()->maybeRecordLoadReason(WouldLoadOutOfProcess);
       // Having no layout object means the frame is not drawn.
       else if (!element->layoutObject())
         frame().document()->maybeRecordLoadReason(WouldLoadDisplayNone);
     } else {
@@ skipping 10 matching lines @@
           frame().document()->maybeRecordLoadReason(WouldLoadAboveAndLeft);
         else if (frameRect().maxY() < 0)
           frame().document()->maybeRecordLoadReason(WouldLoadAbove);
         else if (frameRect().maxX() < 0)
           frame().document()->maybeRecordLoadReason(WouldLoadLeft);
         else if (!m_hiddenForThrottling)
           frame().document()->maybeRecordLoadReason(WouldLoadVisible);
       }
     }
   }
-
-#if DCHECK_IS_ON()
-  // Make sure we never have an unthrottled frame inside a throttled one.
-  while (parent) {
-    DCHECK(canThrottleRendering() || !parent->canThrottleRendering());
-    parent = parent->parentFrameView();
-  }
-#endif
 }
 
 bool FrameView::shouldThrottleRendering() const {
   return canThrottleRendering() && lifecycle().throttlingAllowed();
 }
 
 bool FrameView::canThrottleRendering() const {
+  if (m_lifecycleUpdatesThrottled)
+    return true;
   if (!RuntimeEnabledFeatures::renderingPipelineThrottlingEnabled())
     return false;
-  // We only throttle the rendering pipeline in cross-origin frames. This is
-  // to avoid a situation where an ancestor frame directly depends on the
-  // pipeline timing of a descendant and breaks as a result of throttling.
-  // The rationale is that cross-origin frames must already communicate with
-  // asynchronous messages, so they should be able to tolerate some delay in
-  // receiving replies from a throttled peer.
-  return m_subtreeThrottled ||
-         (m_hiddenForThrottling && m_frame->isCrossOriginSubframe());
+  if (m_subtreeThrottled)
+    return true;
+  // We only throttle hidden cross-origin frames. This is to avoid a situation
+  // where an ancestor frame directly depends on the pipeline timing of a
+  // descendant and breaks as a result of throttling. The rationale is that
+  // cross-origin frames must already communicate with asynchronous messages,
+  // so they should be able to tolerate some delay in receiving replies from a
+  // throttled peer.
+  return m_hiddenForThrottling && m_frame->isCrossOriginSubframe();
+}
+
+void FrameView::beginLifecycleUpdates() {
+  // Avoid pumping frames for the initially empty document.
+  if (!frame().loader().stateMachine()->committedFirstRealDocumentLoad())
+    return;
+  m_lifecycleUpdatesThrottled = false;
+  setupRenderThrottling();
+  updateRenderThrottlingStatus(m_hiddenForThrottling, m_subtreeThrottled);
+  // The compositor will "defer commits" for the main frame until we
+  // explicitly request them.
+  if (frame().isMainFrame())
+    frame().host()->chromeClient().beginLifecycleUpdates();
 }
 
 void FrameView::setInitialViewportSize(const IntSize& viewportSize) {
   if (viewportSize == m_initialViewportSize)
     return;
 
   m_initialViewportSize = viewportSize;
   if (Document* document = m_frame->document())
     document->styleEngine().initialViewportChanged();
 }
 
 int FrameView::initialViewportWidth() const {
   DCHECK(m_frame->isMainFrame());
   return m_initialViewportSize.width();
 }
 
 int FrameView::initialViewportHeight() const {
   DCHECK(m_frame->isMainFrame());
   return m_initialViewportSize.height();
 }
 
 }  // namespace blink