Do not fire didStartLoading and didStopLoading events twice.

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.
  *
  * Redistribution and use in source and binary forms, with or without
@@ skipping 544 matching lines @@
 
 void FrameLoader::updateForSameDocumentNavigation(const KURL& newURL, SameDocumentNavigationSource sameDocumentNavigationSource, PassRefPtr<SerializedScriptValue> data, FrameLoadType type)
 {
     // Update the data source's request with the new URL to fake the URL change
     m_frame->document()->setURL(newURL);
     documentLoader()->setReplacesCurrentHistoryItem(type != FrameLoadTypeStandard);
     documentLoader()->updateForSameDocumentNavigation(newURL, sameDocumentNavigationSource);
 
     // Generate start and stop notifications only when loader is completed so that we
     // don't fire them for fragment redirection that happens in window.onload handler.
-    // See https://bugs.webkit.org/show_bug.cgi?id=31838
-    if (m_frame->document()->loadEventFinished())
+    // See https://bugs.webkit.org/show_bug.cgi?id=31838 and crbug.com/464675
+    if (m_frame->document()->isLoadEventCompleted())
         client()->didStartLoading(NavigationWithinSameDocument);
 
     HistoryCommitType historyCommitType = loadTypeToCommitType(type);
     if (!m_currentItem)
         historyCommitType = HistoryInertCommit;
 
     setHistoryItemStateForCommit(historyCommitType, sameDocumentNavigationSource == SameDocumentNavigationHistoryApi, data);
     client()->dispatchDidNavigateWithinPage(m_currentItem.get(), historyCommitType);
     client()->dispatchDidReceiveTitle(m_frame->document()->title());
-    if (m_frame->document()->loadEventFinished())
+    if (m_frame->document()->isLoadEventCompleted())
         client()->didStopLoading();
 }
 
 void FrameLoader::loadInSameDocument(const KURL& url, PassRefPtr<SerializedScriptValue> stateObject, FrameLoadType type, ClientRedirectPolicy clientRedirect)
 {
     // If we have a state object, we cannot also be a new navigation.
     ASSERT(!stateObject || type == FrameLoadTypeBackForward);
 
     // If we have a provisional request for a different document, a fragment scroll should cancel it.
     if (m_provisionalDocumentLoader) {
@@ skipping 836 matching lines @@
 
     // FIXME: We need a way to propagate insecure requests policy flags to
     // out-of-process frames. For now, we'll always use default behavior.
     if (!parentFrame->isLocalFrame())
         return nullptr;
 
     return toLocalFrame(parentFrame)->document()->insecureNavigationsToUpgrade();
 }
 
 } // namespace blink