Cross-origin iframes: collect data under hypothetical loading strategies

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.
@@ skipping 389 matching lines @@
   Document* document = toDocument(context);
   if (Element* element = document->autofocusElement()) {
     document->setAutofocusElement(0);
     element->focus();
   }
 }
 
 static void recordLoadReasonToHistogram(WouldLoadReason reason) {
   DEFINE_STATIC_LOCAL(
       EnumerationHistogram, unseenFrameHistogram,
-      ("Navigation.DeferredDocumentLoading.StatesV3", WouldLoadReasonEnd));
+      ("Navigation.DeferredDocumentLoading.StatesV4", WouldLoadReasonEnd));
   unseenFrameHistogram.count(reason);
 }
 
 Document::Document(const DocumentInit& initializer,
                    DocumentClassFlags documentClasses)
     : ContainerNode(0, CreateDocument),
       TreeScope(*this),
       m_hasNodesWithPlaceholderStyle(false),
       m_evaluateMediaQueriesOnStyleRecalc(false),
       m_pendingSheetLayout(NoLayoutWithPendingSheets),
@@ skipping 76 matching lines @@
       m_compositorPendingAnimations(new CompositorPendingAnimations()),
       m_templateDocumentHost(nullptr),
       m_didAssociateFormControlsTimer(
           TaskRunnerHelper::get(TaskType::Internal, this),
           this,
           &Document::didAssociateFormControlsTimerFired),
       m_timers(TaskRunnerHelper::get(TaskType::Timer, this)->clone()),
       m_hasViewportUnits(false),
       m_parserSyncPolicy(AllowAsynchronousParsing),
       m_nodeCount(0),
-      m_wouldLoadReason(Created),
+      m_wouldLoadReason(Invalid),
       m_passwordCount(0) {
   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);
 
     CustomElementRegistry* registry =
         m_frame->localDOMWindow()
@@ skipping 5877 matching lines @@
   visitor->trace(m_propertyRegistry);
   visitor->trace(m_styleReattachDataMap);
   Supplementable<Document>::trace(visitor);
   TreeScope::trace(visitor);
   ContainerNode::trace(visitor);
   ExecutionContext::trace(visitor);
   SecurityContext::trace(visitor);
   SynchronousMutationNotifier::trace(visitor);
 }
 
-void Document::maybeRecordLoadReason(WouldLoadReason reason) {
-  DCHECK(m_wouldLoadReason == Created || reason != Created);
+void Document::recordDeferredLoadReason(WouldLoadReason reason) {
+  DCHECK(m_wouldLoadReason == Invalid || reason != Created);
+  DCHECK(reason != Invalid);
   DCHECK(frame());
-  if (m_wouldLoadReason == Created && frame()->isCrossOriginSubframe() &&
-      frame()->loader().stateMachine()->committedFirstRealDocumentLoad()) {
-    recordLoadReasonToHistogram(reason);
-  }
+  DCHECK(frame()->isCrossOriginSubframe());
+  if (reason <= m_wouldLoadReason ||
+      !frame()->loader().stateMachine()->committedFirstRealDocumentLoad())
+    return;
+  for (int i = m_wouldLoadReason + 1; i <= reason; ++i)

[ojan, 2016/11/22 00:41:59]

I think this means that passing WouldLoadNoParent would make it so that all of
the other WouldLoad* reasons would get set as well. Is that what you're
intending?

[dgrogan, 2016/11/29 00:57:32]

Intentional; it's simpler to subtract in the postprocessing step than it is to
make this code do something smarter. But changing from manhattan distance will
make this code more complicated so it might make sense to go ahead and give
WouldLoadNoParent special treatment here.

+    recordLoadReasonToHistogram(static_cast<WouldLoadReason>(i));
   m_wouldLoadReason = reason;
 }
 
 DEFINE_TRACE_WRAPPERS(Document) {
   visitor->traceWrappers(m_importsController);
   visitor->traceWrappers(m_implementation);
   visitor->traceWrappers(m_styleSheetList);
   visitor->traceWrappers(m_styleEngine);
   for (int i = 0; i < numNodeListInvalidationTypes; ++i) {
     for (auto list : m_nodeLists[i]) {
@@ skipping 20 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