Throttle rendering pipeline for invisible frames

third_party/WebKit/Source/core/dom/Document.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  *           (C) 2006 Alexey Proskuryakov (ap@webkit.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2011, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (C) 2008, 2009, 2011, 2012 Google Inc. All rights reserved.
  * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies)
  * Copyright (C) Research In Motion Limited 2010-2011. All rights reserved.
@@ skipping 1513 matching lines @@
         return false;
     return true;
 }
 
 void Document::scheduleLayoutTreeUpdate()
 {
     ASSERT(!hasPendingStyleRecalc());
     ASSERT(shouldScheduleLayoutTreeUpdate());
     ASSERT(needsLayoutTreeUpdate());
 
-    page()->animator().scheduleVisualUpdate();
+    if (!view()->shouldThrottleRendering())
+        page()->animator().scheduleVisualUpdate();
     m_lifecycle.ensureStateAtMost(DocumentLifecycle::VisualUpdatePending);
 
     TRACE_EVENT_INSTANT1(TRACE_DISABLED_BY_DEFAULT("devtools.timeline"), "ScheduleStyleRecalculation", TRACE_EVENT_SCOPE_THREAD, "data", InspectorRecalculateStylesEvent::data(frame()));
     InspectorInstrumentation::didScheduleStyleRecalculation(this);
 
     ++m_styleVersion;
 }
 
 bool Document::hasPendingForcedStyleRecalc() const
 {
@@ skipping 169 matching lines @@
 
 void Document::updateLayoutTree(StyleRecalcChange change)
 {
     ASSERT(isMainThread());
 
     ScriptForbiddenScope forbidScript;
 
     if (!view() || !isActive())
         return;
 
+    if (view()->shouldThrottleRendering())
+        return;
+
     if (change != Force && !needsLayoutTreeUpdate()) {
         ASSERT(lifecycle().state() != DocumentLifecycle::VisualUpdatePending);
         return;
     }
 
     if (inStyleRecalc())
         return;
 
     // Entering here from inside layout or paint would be catastrophic since recalcStyle can
     // tear down the layout tree or (unfortunately) run script. Kill the whole layoutObject if
@@ skipping 47 matching lines @@
     TRACE_EVENT_END1("blink,devtools.timeline", "UpdateLayoutTree", "elementCount", m_styleRecalcElementCounter);
     InspectorInstrumentation::didRecalculateStyle(cookie, m_styleRecalcElementCounter);
 
 #if ENABLE(ASSERT)
     assertLayoutTreeUpdated(*this);
 #endif
 }
 
 void Document::updateStyle(StyleRecalcChange change)
 {
+    if (view()->shouldThrottleRendering())
+        return;
+
     TRACE_EVENT_BEGIN0("blink,blink_style", "Document::updateStyle");
     unsigned initialResolverAccessCount = styleEngine().resolverAccessCount();
 
     HTMLFrameOwnerElement::UpdateSuspendScope suspendWidgetHierarchyUpdates;
     m_lifecycle.advanceTo(DocumentLifecycle::InStyleRecalc);
 
     NthIndexCache nthIndexCache(*this);
 
     if (styleChangeType() >= SubtreeStyleChange)
         change = Force;
@@ skipping 157 matching lines @@
 }
 
 // FIXME: This is a bad idea and needs to be removed eventually.
 // Other browsers load stylesheets before they continue parsing the web page.
 // Since we don't, we can run JavaScript code that needs answers before the
 // stylesheets are loaded. Doing a layout ignoring the pending stylesheets
 // lets us get reasonable answers. The long term solution to this problem is
 // to instead suspend JavaScript execution.
 void Document::updateLayoutIgnorePendingStylesheets(Document::RunPostLayoutTasks runPostLayoutTasks)
 {
+    DocumentLifecycle::PreventThrottlingScope preventThrottling(lifecycle());
     StyleEngine::IgnoringPendingStylesheet ignoring(styleEngine());
 
     if (styleEngine().hasPendingSheets()) {
         // FIXME: We are willing to attempt to suppress painting with outdated style info only once.
         // Our assumption is that it would be dangerous to try to stop it a second time, after page
         // content has already been loaded and displayed with accurate style information. (Our
         // suppression involves blanking the whole page at the moment. If it were more refined, we
         // might be able to do something better.) It's worth noting though that this entire method
         // is a hack, since what we really want to do is suspend JS instead of doing a layout with
         // inaccurate information.
@@ skipping 3833 matching lines @@
 #ifndef NDEBUG
 using namespace blink;
 void showLiveDocumentInstances()
 {
     Document::WeakDocumentSet& set = Document::liveDocumentSet();
     fprintf(stderr, "There are %u documents currently alive:\n", set.size());
     for (Document* document : set)
         fprintf(stderr, "- Document %p URL: %s\n", document, document->url().string().utf8().data());
 }
 #endif