Always send a fail or finish notification for each navigation.

third_party/WebKit/Source/core/loader/FrameLoader.cpp

 /*
  * Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All rights
  * reserved.
  * Copyright (C) 2008 Nokia Corporation and/or its subsidiary(-ies)
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved.
  * (http://www.torchmobile.com/)
  * Copyright (C) 2008 Alp Toker <alp@atoker.com>
  * Copyright (C) Research In Motion Limited 2009. All rights reserved.
  * Copyright (C) 2011 Kris Jordan <krisjordan@gmail.com>
  * Copyright (C) 2011 Google Inc. All rights reserved.
@@ skipping 208 matching lines @@
   initialRequest.setFrameType(m_frame->isMainFrame()
                                   ? WebURLRequest::FrameTypeTopLevel
                                   : WebURLRequest::FrameTypeNested);
   m_provisionalDocumentLoader =
       client()->createDocumentLoader(m_frame, initialRequest, SubstituteData(),
                                      ClientRedirectPolicy::NotClientRedirect);
   m_provisionalDocumentLoader->startLoadingMainResource();
   m_frame->document()->cancelParsing();
   m_stateMachine.advanceTo(
       FrameLoaderStateMachine::DisplayingInitialEmptyDocument);
+  // Suppress finish notifications for inital empty documents, since they don't
+  // generate start notifications.

[dcheng, 2016/12/14 23:01:28]

Unrelated, but do you think it'd be problematic to send start / finish for
initial empty documents?

[Nate Chapin, 2016/12/14 23:59:18]

Extensions might inject content scripts into initial empty documents? I haven't
tested to see what if anything would break, it's just been the convention to
keep the initial empty document as a mostly-invisible blink implementation
detail.

+  if (m_documentLoader)
+    m_documentLoader->setSentDidFinishLoad();
   // Self-suspend if created in an already suspended Page. Note that both
   // startLoadingMainResource() and cancelParsing() may have already detached
   // the frame, since they both fire JS events.
   if (m_frame->page() && m_frame->page()->suspended())
     setDefersLoading(true);
   takeObjectSnapshot();
 }
 
 FrameLoaderClient* FrameLoader::client() const {
   return static_cast<FrameLoaderClient*>(m_frame->client());
@@ skipping 427 matching lines @@
   if (!document->haveImportsLoaded())
     return false;
   if (document->fetcher()->requestCount())
     return false;
   if (document->isDelayingLoadEvent())
     return false;
   return allDescendantsAreComplete(document->frame());
 }
 
 static bool shouldSendFinishNotification(LocalFrame* frame) {
-  // Don't send stop notifications for inital empty documents, since they don't
-  // generate start notifications.
-  if (!frame->loader().stateMachine()->committedFirstRealDocumentLoad())

[Nate Chapin, 2016/12/12 21:40:38]

setSentDidFinishLoad() in init() instead.

-    return false;
-
   // Don't send didFinishLoad more than once per DocumentLoader.
   if (frame->loader().documentLoader()->sentDidFinishLoad())
     return false;
 
   // We might have declined to run the load event due to an imminent
   // content-initiated navigation.
   if (!frame->document()->loadEventFinished())
     return false;
 
   // An event might have restarted a child frame.
@@ skipping 771 matching lines @@
 void FrameLoader::loadFailed(DocumentLoader* loader,
                              const ResourceError& error) {
   if (!error.isCancellation() && m_frame->owner()) {
     // FIXME: For now, fallback content doesn't work cross process.
     if (m_frame->owner()->isLocal())
       m_frame->deprecatedLocalOwner()->renderFallbackContent();
   }
 
   HistoryCommitType historyCommitType = loadTypeToCommitType(m_loadType);
   if (loader == m_provisionalDocumentLoader) {
+    m_provisionalDocumentLoader->setSentDidFinishLoad();
     client()->dispatchDidFailProvisionalLoad(error, historyCommitType);
     if (loader != m_provisionalDocumentLoader)
       return;
     detachDocumentLoader(m_provisionalDocumentLoader);
-    m_progressTracker->progressCompleted();

[Nate Chapin, 2016/12/12 21:40:38]

progressCompleted() should be called if appropriate in the checkCompleted() call
below, so long as setSentDidFinishLoad() is called.

[dcheng, 2016/12/14 23:01:28]

Seems subtle, but I agree this should work.

   } else {
     DCHECK_EQ(loader, m_documentLoader);
     if (m_frame->document()->parser())
       m_frame->document()->parser()->stopParsing();
-    m_documentLoader->setSentDidFinishLoad();
-    if (!m_provisionalDocumentLoader && m_frame->isLoading()) {
+    if (!m_documentLoader->sentDidFinishLoad()) {
+      m_documentLoader->setSentDidFinishLoad();
       client()->dispatchDidFailLoad(error, historyCommitType);
-      m_progressTracker->progressCompleted();
     }
   }
   checkCompleted();
 }
 
 bool FrameLoader::shouldPerformFragmentNavigation(bool isFormSubmission,
                                                   const String& httpMethod,
                                                   FrameLoadType loadType,
                                                   const KURL& url) {
   // We don't do this if we are submitting a form with method other than "GET",
@@ skipping 464 matching lines @@
                          m_documentLoader ? m_documentLoader->url() : String());
   return tracedValue;
 }
 
 inline void FrameLoader::takeObjectSnapshot() const {
   TRACE_EVENT_OBJECT_SNAPSHOT_WITH_ID("loading", "FrameLoader", this,
                                       toTracedValue());
 }
 
 }  // namespace blink