Log to UMA when x-origin frames (1) are created and (2) become visible

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 365 matching lines @@
 // This doesn't work with non-Document ExecutionContext.
 static void runAutofocusTask(ExecutionContext* context)
 {
     Document* document = toDocument(context);
     if (Element* element = document->autofocusElement()) {
         document->setAutofocusElement(0);
         element->focus();
     }
 }
 
+// These are logged to UMA, so don't re-arrange them without creating a new histogram.
+enum DocumentVisibilityForDeferredLoading {
+    Created,
+    WouldLoadBecauseVisible,
+    // TODO(dgrogan): Add WouldLoadBecauseTopOrLeft, WouldLoadBecauseDisplayNone, etc
+
+    DocumentVisibilityForDeferredLoadingEnd
+};
+
+static void RecordStateToHistogram(DocumentVisibilityForDeferredLoading state)
+{
+    DEFINE_STATIC_LOCAL(EnumerationHistogram, unseenFrameHistogram, ("DeferredFrameLoading.StatesV1", DocumentVisibilityForDeferredLoadingEnd));
+    unseenFrameHistogram.count(state);
+}
+
 Document::Document(const DocumentInit& initializer, DocumentClassFlags documentClasses)
     : ContainerNode(0, CreateDocument)
     , TreeScope(*this)
     , m_hasNodesWithPlaceholderStyle(false)
     , m_evaluateMediaQueriesOnStyleRecalc(false)
     , m_pendingSheetLayout(NoLayoutWithPendingSheets)
     , m_frame(initializer.frame())
     , m_domWindow(m_frame ? m_frame->localDOMWindow() : 0)
     , m_importsController(initializer.importsController())
     , m_contextFeatures(ContextFeatures::defaultSwitch())
@@ skipping 51 matching lines @@
     , m_registrationContext(initializer.registrationContext(this))
     , m_elementDataCacheClearTimer(this, &Document::elementDataCacheClearTimerFired)
     , m_timeline(DocumentTimeline::create(this))
     , m_compositorPendingAnimations(new CompositorPendingAnimations())
     , m_templateDocumentHost(nullptr)
     , m_didAssociateFormControlsTimer(this, &Document::didAssociateFormControlsTimerFired)
     , m_timers(TaskRunnerHelper::get(TaskType::Timer, this)->clone())
     , m_hasViewportUnits(false)
     , m_parserSyncPolicy(AllowAsynchronousParsing)
     , m_nodeCount(0)
+    , m_visibilityWasLogged(false)
 {
     if (m_frame) {
         DCHECK(m_frame->page());
         provideContextFeaturesToDocumentFrom(*this, *m_frame->page());
 
         m_fetcher = m_frame->loader().documentLoader()->fetcher();
         FrameFetchContext::provideDocumentToContext(m_fetcher->context(), this);
 
         CustomElementsRegistry* registry = m_frame->localDOMWindow()
             ? m_frame->localDOMWindow()->maybeCustomElements()
@@ skipping 10 matching lines @@
 
     // We depend on the url getting immediately set in subframes, but we
     // also depend on the url NOT getting immediately set in opened windows.
     // See fast/dom/early-frame-url.html
     // and fast/dom/location-new-window-no-crash.html, respectively.
     // FIXME: Can/should we unify this behavior?
     if (initializer.shouldSetURL())
         setURL(initializer.url());
 
     initSecurityContext(initializer);
+    if (frame() && getSecurityOrigin() && frame()->tree().top()->securityContext() && !getSecurityOrigin()->canAccess(frame()->tree().top()->securityContext()->getSecurityOrigin()))

[dcheng, 2016/08/29 20:37:19]

I don't think securityOrigin can be null here, unless something is really
broken.

[dgrogan, 2016/08/31 19:52:41]

Good to know, changed to DCHECK.

+        RecordStateToHistogram(Created);
+
     initDNSPrefetch();
 
     InstanceCounters::incrementCounter(InstanceCounters::DocumentCounter);
 
     m_lifecycle.advanceTo(DocumentLifecycle::Inactive);
 
     // Since CSSFontSelector requires Document::m_fetcher and StyleEngine owns
     // CSSFontSelector, need to initialize m_styleEngine after initializing
     // m_fetcher.
     m_styleEngine = StyleEngine::create(*this);
@@ skipping 5503 matching lines @@
     visitor->trace(m_intersectionObserverData);
     visitor->trace(m_snapCoordinator);
     visitor->trace(m_resizeObserverController);
     Supplementable<Document>::trace(visitor);
     TreeScope::trace(visitor);
     ContainerNode::trace(visitor);
     ExecutionContext::trace(visitor);
     SecurityContext::trace(visitor);
 }
 
+void Document::onVisibilityMaybeChanged(bool visible)
+{
+    if (visible && !m_visibilityWasLogged && frame() && frame()->isCrossOriginSubframe()) {

[dcheng, 2016/08/29 20:37:19]

Since frame()->document() points to this document(), frame() should not be null.
Let's just DCHECK()?

[dgrogan, 2016/08/31 19:52:41]

Done.

+        m_visibilityWasLogged = true;
+        RecordStateToHistogram(WouldLoadBecauseVisible);
+    }
+}
+
 DEFINE_TRACE_WRAPPERS(Document)
 {
     visitor->traceWrappers(m_importsController);
     visitor->traceWrappers(m_implementation);
     visitor->traceWrappers(m_styleSheetList);
     visitor->traceWrappers(m_styleEngine);
     visitor->traceWrappers(
         Supplementable<Document>::m_supplements.get(
             FontFaceSet::supplementName()));
     for (int i = 0; i < numNodeListInvalidationTypes; ++i) {
@@ skipping 18 matching lines @@
 }
 
 void showLiveDocumentInstances()
 {
     WeakDocumentSet& set = 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().getString().utf8().data());
 }
 #endif