/*
 * 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
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1.  Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 * 2.  Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 * 3.  Neither the name of Apple Computer, Inc. ("Apple") nor the names of
 *     its contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include "core/loader/FrameLoader.h"

#include "bindings/core/v8/DOMWrapperWorld.h"
#include "bindings/core/v8/ScriptController.h"
#include "bindings/core/v8/SerializedScriptValue.h"
#include "core/HTMLNames.h"
#include "core/dom/Document.h"
#include "core/dom/Element.h"
#include "core/dom/ViewportDescription.h"
#include "core/editing/Editor.h"
#include "core/editing/commands/UndoStack.h"
#include "core/events/GestureEvent.h"
#include "core/events/KeyboardEvent.h"
#include "core/events/MouseEvent.h"
#include "core/events/PageTransitionEvent.h"
#include "core/fetch/ResourceFetcher.h"
#include "core/fetch/ResourceLoader.h"
#include "core/frame/FrameHost.h"
#include "core/frame/FrameView.h"
#include "core/frame/LocalDOMWindow.h"
#include "core/frame/LocalFrame.h"
#include "core/frame/Settings.h"
#include "core/frame/VisualViewport.h"
#include "core/frame/csp/ContentSecurityPolicy.h"
#include "core/html/HTMLFormElement.h"
#include "core/html/HTMLFrameOwnerElement.h"
#include "core/html/parser/HTMLParserIdioms.h"
#include "core/input/EventHandler.h"
#include "core/inspector/ConsoleMessage.h"
#include "core/inspector/InspectorInstrumentation.h"
#include "core/inspector/InstanceCounters.h"
#include "core/loader/DocumentLoadTiming.h"
#include "core/loader/DocumentLoader.h"
#include "core/loader/FormSubmission.h"
#include "core/loader/FrameLoadRequest.h"
#include "core/loader/FrameLoaderClient.h"
#include "core/loader/LinkLoader.h"
#include "core/loader/MixedContentChecker.h"
#include "core/loader/NavigationScheduler.h"
#include "core/loader/NetworkHintsInterface.h"
#include "core/loader/ProgressTracker.h"
#include "core/loader/appcache/ApplicationCacheHost.h"
#include "core/page/ChromeClient.h"
#include "core/page/CreateWindow.h"
#include "core/page/FrameTree.h"
#include "core/page/Page.h"
#include "core/page/WindowFeatures.h"
#include "core/page/scrolling/ScrollingCoordinator.h"
#include "core/svg/graphics/SVGImage.h"
#include "core/xml/parser/XMLDocumentParser.h"
#include "platform/Logging.h"
#include "platform/PluginScriptForbiddenScope.h"
#include "platform/ScriptForbiddenScope.h"
#include "platform/UserGestureIndicator.h"
#include "platform/network/HTTPParsers.h"
#include "platform/network/ResourceRequest.h"
#include "platform/scroll/ScrollAnimatorBase.h"
#include "platform/weborigin/SecurityOrigin.h"
#include "platform/weborigin/SecurityPolicy.h"
#include "platform/weborigin/Suborigin.h"
#include "public/platform/WebURLRequest.h"
#include "wtf/TemporaryChange.h"
#include "wtf/text/CString.h"
#include "wtf/text/WTFString.h"

using blink::WebURLRequest;

namespace blink {

using namespace HTMLNames;

bool isBackForwardLoadType(FrameLoadType type)
{
    return type == FrameLoadTypeBackForward || type == FrameLoadTypeInitialHistoryLoad;
}

static bool needsHistoryItemRestore(FrameLoadType type)
{
    return type == FrameLoadTypeBackForward || type == FrameLoadTypeReload
        || type == FrameLoadTypeReloadFromOrigin;
}

// static
ResourceRequest FrameLoader::resourceRequestFromHistoryItem(HistoryItem* item,
    ResourceRequestCachePolicy cachePolicy)
{
    RefPtr<EncodedFormData> formData = item->formData();
    ResourceRequest request(item->url());
    request.setHTTPReferrer(item->referrer());
    request.setCachePolicy(cachePolicy);
    if (formData) {
        request.setHTTPMethod(HTTPNames::POST);
        request.setHTTPBody(formData);
        request.setHTTPContentType(item->formContentType());
        RefPtr<SecurityOrigin> securityOrigin = SecurityOrigin::createFromString(item->referrer().referrer);
        request.addHTTPOriginIfNeeded(securityOrigin);
    }
    return request;
}

ResourceRequest FrameLoader::resourceRequestForReload(FrameLoadType frameLoadType,
    const KURL& overrideURL, ClientRedirectPolicy clientRedirectPolicy)
{
    ASSERT(frameLoadType == FrameLoadTypeReload || frameLoadType == FrameLoadTypeReloadFromOrigin);
    ResourceRequestCachePolicy cachePolicy = frameLoadType == FrameLoadTypeReloadFromOrigin ?
        ReloadBypassingCache : ReloadIgnoringCacheData;
    if (!m_currentItem)
        return ResourceRequest();
    ResourceRequest request = resourceRequestFromHistoryItem(m_currentItem.get(), cachePolicy);

    // ClientRedirectPolicy is an indication that this load was triggered by
    // some direct interaction with the page. If this reload is not a client
    // redirect, we should reuse the referrer from the original load of the
    // current document. If this reload is a client redirect (e.g., location.reload()),
    // it was initiated by something in the current document and should
    // therefore show the current document's url as the referrer.
    if (clientRedirectPolicy == ClientRedirect) {
        request.setHTTPReferrer(Referrer(m_frame->document()->outgoingReferrer(),
            m_frame->document()->getReferrerPolicy()));
    }

    if (!overrideURL.isEmpty()) {
        request.setURL(overrideURL);
        request.clearHTTPReferrer();
    }
    request.setSkipServiceWorker(frameLoadType == FrameLoadTypeReloadFromOrigin);
    return request;
}

FrameLoader::FrameLoader(LocalFrame* frame)
    : m_frame(frame)
    , m_progressTracker(ProgressTracker::create(frame))
    , m_loadType(FrameLoadTypeStandard)
    , m_inStopAllLoaders(false)
    , m_checkTimer(this, &FrameLoader::checkTimerFired)
    , m_didAccessInitialDocument(false)
    , m_didAccessInitialDocumentTimer(this, &FrameLoader::didAccessInitialDocumentTimerFired)
    , m_forcedSandboxFlags(SandboxNone)
    , m_dispatchingDidClearWindowObjectInMainWorld(false)
    , m_protectProvisionalLoader(false)
{
}

FrameLoader::~FrameLoader()
{
    // Verify that this FrameLoader has been detached.
    ASSERT(!m_progressTracker);
}

DEFINE_TRACE(FrameLoader)
{
    visitor->trace(m_frame);
    visitor->trace(m_progressTracker);
    visitor->trace(m_documentLoader);
    visitor->trace(m_provisionalDocumentLoader);
    visitor->trace(m_currentItem);
    visitor->trace(m_provisionalItem);
    visitor->trace(m_deferredHistoryLoad);
}

void FrameLoader::init()
{
    // init() may dispatch JS events, so protect a reference to m_frame.
    RefPtrWillBeRawPtr<LocalFrame> protect(m_frame.get());
    ResourceRequest initialRequest(KURL(ParsedURLString, emptyString()));
    initialRequest.setRequestContext(WebURLRequest::RequestContextInternal);
    initialRequest.setFrameType(m_frame->isMainFrame() ? WebURLRequest::FrameTypeTopLevel : WebURLRequest::FrameTypeNested);
    m_provisionalDocumentLoader = client()->createDocumentLoader(m_frame, initialRequest, SubstituteData());
    m_provisionalDocumentLoader->startLoadingMainResource();
    m_frame->document()->cancelParsing();
    m_stateMachine.advanceTo(FrameLoaderStateMachine::DisplayingInitialEmptyDocument);
}

FrameLoaderClient* FrameLoader::client() const
{
    return static_cast<FrameLoaderClient*>(m_frame->client());
}

void FrameLoader::setDefersLoading(bool defers)
{
    if (m_provisionalDocumentLoader)
        m_provisionalDocumentLoader->fetcher()->setDefersLoading(defers);

    if (Document* document = m_frame->document()) {
        document->fetcher()->setDefersLoading(defers);
        if (defers)
            document->suspendScheduledTasks();
        else
            document->resumeScheduledTasks();
    }

    if (!defers) {
        if (m_deferredHistoryLoad) {
            load(FrameLoadRequest(nullptr, m_deferredHistoryLoad->m_request),
                m_deferredHistoryLoad->m_loadType, m_deferredHistoryLoad->m_item.get(),
                m_deferredHistoryLoad->m_historyLoadType);
            m_deferredHistoryLoad.clear();
        }
        m_frame->navigationScheduler().startTimer();
        scheduleCheckCompleted();
    }
}

void FrameLoader::saveScrollState()
{
    if (!m_currentItem || !m_frame->view())
        return;

    // Shouldn't clobber anything if we might still restore later.
    if (needsHistoryItemRestore(m_loadType) && m_documentLoader && !m_documentLoader->initialScrollState().wasScrolledByUser)
        return;

    if (ScrollableArea* layoutScrollableArea = m_frame->view()->layoutViewportScrollableArea())
        m_currentItem->setScrollPoint(layoutScrollableArea->scrollPosition());
    m_currentItem->setVisualViewportScrollPoint(m_frame->host()->visualViewport().visibleRect().location());

    if (m_frame->isMainFrame())
        m_currentItem->setPageScaleFactor(m_frame->page()->pageScaleFactor());

    client()->didUpdateCurrentHistoryItem();
}

void FrameLoader::dispatchUnloadEvent()
{
    // If the frame is unloading, the provisional loader should no longer be
    // protected. It will be detached soon.
    m_protectProvisionalLoader = false;
    saveScrollState();

    if (m_frame->document() && !SVGImage::isInSVGImage(m_frame->document()))
        m_frame->document()->dispatchUnloadEvents();

    if (Page* page = m_frame->page())
        page->undoStack().didUnloadFrame(*m_frame);
}

void FrameLoader::didExplicitOpen()
{
    // Calling document.open counts as committing the first real document load.
    if (!m_stateMachine.committedFirstRealDocumentLoad())
        m_stateMachine.advanceTo(FrameLoaderStateMachine::CommittedFirstRealLoad);

    // Only model a document.open() as part of a navigation if its parent is not done
    // or in the process of completing.
    if (Frame* parent = m_frame->tree().parent()) {
        if ((parent->isLocalFrame() && toLocalFrame(parent)->document()->loadEventStillNeeded())
            || (parent->isRemoteFrame() && parent->isLoading())) {
            m_progressTracker->progressStarted();
        }
    }

    // Prevent window.open(url) -- eg window.open("about:blank") -- from blowing away results
    // from a subsequent window.document.open / window.document.write call.
    // Canceling redirection here works for all cases because document.open
    // implicitly precedes document.write.
    m_frame->navigationScheduler().cancel();
}

void FrameLoader::clear()
{
    // clear() is called during (Local)Frame detachment or when
    // reusing a FrameLoader by putting a new Document within it
    // (DocumentLoader::ensureWriter().)
    if (m_stateMachine.creatingInitialEmptyDocument())
        return;

    m_frame->editor().clear();
    m_frame->document()->removeFocusedElementOfSubtree(m_frame->document());
    m_frame->selection().prepareForDestruction();
    m_frame->eventHandler().clear();
    if (m_frame->view())
        m_frame->view()->clear();

    m_frame->script().enableEval();

    m_frame->navigationScheduler().cancel();

    m_checkTimer.stop();

    if (m_stateMachine.isDisplayingInitialEmptyDocument())
        m_stateMachine.advanceTo(FrameLoaderStateMachine::CommittedFirstRealLoad);
}

// This is only called by ScriptController::executeScriptIfJavaScriptURL
// and always contains the result of evaluating a javascript: url.
// This is the <iframe src="javascript:'html'"> case.
void FrameLoader::replaceDocumentWhileExecutingJavaScriptURL(const String& source, Document* ownerDocument)
{
    if (!m_frame->document()->loader() || m_frame->document()->pageDismissalEventBeingDispatched() != Document::NoDismissal)
        return;

    // DocumentLoader::replaceDocumentWhileExecutingJavaScriptURL can cause the DocumentLoader to get deref'ed and possible destroyed,
    // so protect it with a RefPtr.
    RefPtrWillBeRawPtr<DocumentLoader> documentLoader(m_frame->document()->loader());

    UseCounter::count(*m_frame->document(), UseCounter::ReplaceDocumentViaJavaScriptURL);

    // Prepare a DocumentInit before clearing the frame, because it may need to
    // inherit an aliased security context.
    DocumentInit init(ownerDocument, m_frame->document()->url(), m_frame);
    init.withNewRegistrationContext();

    stopAllLoaders();
    // Don't allow any new child frames to load in this frame: attaching a new
    // child frame during or after detaching children results in an attached
    // frame on a detached DOM tree, which is bad.
    SubframeLoadingDisabler disabler(m_frame->document());
    m_frame->detachChildren();
    m_frame->document()->detach();
    clear();

    // detachChildren() potentially detaches the frame from the document. The
    // loading cannot continue in that case.
    if (!m_frame->page())
        return;

    client()->transitionToCommittedForNewPage();
    documentLoader->replaceDocumentWhileExecutingJavaScriptURL(init, source);
}

void FrameLoader::receivedMainResourceRedirect(const KURL& newURL)
{
    client()->dispatchDidReceiveServerRedirectForProvisionalLoad();
    // If a back/forward navigation redirects cross-origin, don't reuse any state from the HistoryItem.
    if (m_provisionalItem && !SecurityOrigin::create(m_provisionalItem->url())->isSameSchemeHostPort(SecurityOrigin::create(newURL).get()))
        m_provisionalItem.clear();
}

void FrameLoader::setHistoryItemStateForCommit(HistoryCommitType historyCommitType, HistoryNavigationType navigationType)
{
    RefPtrWillBeRawPtr<HistoryItem> oldItem = m_currentItem;
    if (historyCommitType == BackForwardCommit && m_provisionalItem)
        m_currentItem = m_provisionalItem.release();
    else
        m_currentItem = HistoryItem::create();
    m_currentItem->setURL(m_documentLoader->urlForHistory());
    m_currentItem->setDocumentState(m_frame->document()->formElementsState());
    m_currentItem->setTarget(m_frame->tree().uniqueName());
    m_currentItem->setReferrer(SecurityPolicy::generateReferrer(m_documentLoader->request().getReferrerPolicy(), m_currentItem->url(), m_documentLoader->request().httpReferrer()));
    m_currentItem->setFormInfoFromRequest(m_documentLoader->request());

    // Don't propagate state from the old item to the new item if there isn't an old item (obviously),
    // or if this is a back/forward navigation, since we explicitly want to restore the state we just
    // committed.
    if (!oldItem || historyCommitType == BackForwardCommit)
        return;
    // Don't propagate state from the old item if this is a different-document navigation, unless the before
    // and after pages are logically related. This means they have the same url (ignoring fragment) and
    // the new item was loaded via reload or client redirect.
    if (navigationType == HistoryNavigationType::DifferentDocument && (historyCommitType != HistoryInertCommit || !equalIgnoringFragmentIdentifier(oldItem->url(), m_currentItem->url())))
        return;
    m_currentItem->setDocumentSequenceNumber(oldItem->documentSequenceNumber());
    m_currentItem->setScrollPoint(oldItem->scrollPoint());
    m_currentItem->setVisualViewportScrollPoint(oldItem->visualViewportScrollPoint());
    m_currentItem->setPageScaleFactor(oldItem->pageScaleFactor());
    m_currentItem->setScrollRestorationType(oldItem->scrollRestorationType());

    // The item sequence number determines whether items are "the same", such back/forward navigation
    // between items with the same item sequence number is a no-op. Only treat this as identical if the
    // navigation did not create a back/forward entry and the url is identical or it was loaded via
    // history.replaceState().
    if (historyCommitType == HistoryInertCommit && (navigationType == HistoryNavigationType::HistoryApi || oldItem->url() == m_currentItem->url())) {
        m_currentItem->setStateObject(oldItem->stateObject());
        m_currentItem->setItemSequenceNumber(oldItem->itemSequenceNumber());
    }
}

static HistoryCommitType loadTypeToCommitType(FrameLoadType type)
{
    switch (type) {
    case FrameLoadTypeStandard:
        return StandardCommit;
    case FrameLoadTypeInitialInChildFrame:
    case FrameLoadTypeInitialHistoryLoad:
        return InitialCommitInChildFrame;
    case FrameLoadTypeBackForward:
        return BackForwardCommit;
    default:
        break;
    }
    return HistoryInertCommit;
}

void FrameLoader::receivedFirstData()
{
    if (m_stateMachine.creatingInitialEmptyDocument())
        return;

    HistoryCommitType historyCommitType = loadTypeToCommitType(m_loadType);
    if (historyCommitType == StandardCommit && (m_documentLoader->urlForHistory().isEmpty() || (opener() && !m_currentItem && m_documentLoader->originalRequest().url().isEmpty())))
        historyCommitType = HistoryInertCommit;
    else if (historyCommitType == InitialCommitInChildFrame && MixedContentChecker::isMixedContent(m_frame->tree().top()->securityContext()->getSecurityOrigin(), m_documentLoader->url()))
        historyCommitType = HistoryInertCommit;
    setHistoryItemStateForCommit(historyCommitType, HistoryNavigationType::DifferentDocument);

    if (!m_stateMachine.committedMultipleRealLoads() && m_loadType == FrameLoadTypeStandard)
        m_stateMachine.advanceTo(FrameLoaderStateMachine::CommittedMultipleRealLoads);

    client()->dispatchDidCommitLoad(m_currentItem.get(), historyCommitType);

    TRACE_EVENT1("devtools.timeline", "CommitLoad", "data", InspectorCommitLoadEvent::data(m_frame));
    InspectorInstrumentation::didCommitLoad(m_frame, m_documentLoader.get());
    m_frame->page()->didCommitLoad(m_frame);
    dispatchDidClearDocumentOfWindowObject();
}

void FrameLoader::didBeginDocument(bool dispatch)
{
    ASSERT(m_frame);
    ASSERT(m_frame->document());
    ASSERT(m_frame->document()->fetcher());
    m_frame->document()->setReadyState(Document::Loading);

    if (dispatch)
        dispatchDidClearDocumentOfWindowObject();

    m_frame->document()->initContentSecurityPolicy(m_documentLoader ? m_documentLoader->releaseContentSecurityPolicy() : ContentSecurityPolicy::create());

    if (m_documentLoader) {
        String suboriginHeader = m_documentLoader->response().httpHeaderField(HTTPNames::Suborigin);
        if (!suboriginHeader.isNull()) {
            Vector<String> messages;
            Suborigin suborigin;
            if (parseSuboriginHeader(suboriginHeader, &suborigin, messages))
                m_frame->document()->enforceSuborigin(suborigin);

            for (auto& message : messages)
                m_frame->document()->addConsoleMessage(ConsoleMessage::create(SecurityMessageSource, ErrorMessageLevel, "Error with Suborigin header: " + message));
        }
    }

    if (m_documentLoader) {
        m_frame->document()->clientHintsPreferences().updateFrom(m_documentLoader->clientHintsPreferences());
        LinkLoader::loadLinksFromHeader(m_documentLoader->response().httpHeaderField(HTTPNames::Link), m_documentLoader->response().url(),
            m_frame->document(), NetworkHintsInterfaceImpl(), LinkLoader::OnlyLoadResources);
    }

    Settings* settings = m_frame->document()->settings();
    if (settings) {
        m_frame->document()->fetcher()->setImagesEnabled(settings->imagesEnabled());
        m_frame->document()->fetcher()->setAutoLoadImages(settings->loadsImagesAutomatically());
    }

    if (m_documentLoader) {
        const AtomicString& dnsPrefetchControl = m_documentLoader->response().httpHeaderField(HTTPNames::X_DNS_Prefetch_Control);
        if (!dnsPrefetchControl.isEmpty())
            m_frame->document()->parseDNSPrefetchControlHeader(dnsPrefetchControl);

        String headerContentLanguage = m_documentLoader->response().httpHeaderField(HTTPNames::Content_Language);
        if (!headerContentLanguage.isEmpty()) {
            size_t commaIndex = headerContentLanguage.find(',');
            headerContentLanguage.truncate(commaIndex); // kNotFound == -1 == don't truncate
            headerContentLanguage = headerContentLanguage.stripWhiteSpace(isHTMLSpace<UChar>);
            if (!headerContentLanguage.isEmpty())
                m_frame->document()->setContentLanguage(AtomicString(headerContentLanguage));
        }
    }

    if (m_provisionalItem && isBackForwardLoadType(m_loadType))
        m_frame->document()->setStateForNewFormElements(m_provisionalItem->documentState());

    client()->didCreateNewDocument();
}

void FrameLoader::finishedParsing()
{
    if (m_stateMachine.creatingInitialEmptyDocument())
        return;

    // This can be called from the LocalFrame's destructor, in which case we shouldn't protect ourselves
    // because doing so will cause us to re-enter the destructor when protector goes out of scope.
    // Null-checking the FrameView indicates whether or not we're in the destructor.
    RefPtrWillBeRawPtr<LocalFrame> protect(m_frame->view() ? m_frame.get() : nullptr);

    m_progressTracker->finishedParsing();

    if (client()) {
        ScriptForbiddenScope forbidScripts;
        client()->dispatchDidFinishDocumentLoad(m_documentLoader ? m_documentLoader->isCommittedButEmpty() : true);
    }

    if (client())
        client()->runScriptsAtDocumentReady();

    checkCompleted();

    if (!m_frame->view())
        return; // We are being destroyed by something checkCompleted called.

    // Check if the scrollbars are really needed for the content.
    // If not, remove them, relayout, and repaint.
    m_frame->view()->restoreScrollbar();
    processFragment(m_frame->document()->url(), NavigationToDifferentDocument);
}

static bool allDescendantsAreComplete(Frame* frame)
{
    for (Frame* child = frame->tree().firstChild(); child; child = child->tree().traverseNext(frame)) {
        if (child->isLoading())
            return false;
    }
    return true;
}

bool FrameLoader::allAncestorsAreComplete() const
{
    for (Frame* ancestor = m_frame; ancestor; ancestor = ancestor->tree().parent()) {
        if (ancestor->isLoading())
            return false;
    }
    return true;
}

static bool shouldComplete(Document* document)
{
    if (!document->frame())
        return false;
    if (document->parsing() || document->isInDOMContentLoaded())
        return false;
    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())
        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.
    if (!allDescendantsAreComplete(frame))
        return false;
    return true;
}

static bool shouldSendCompleteNotification(LocalFrame* frame)
{
    // FIXME: We might have already sent stop notifications and be re-completing.
    if (!frame->isLoading())
        return false;
    // Only send didStopLoading() if there are no navigations in progress at all,
    // whether committed, provisional, or pending.
    return frame->loader().documentLoader()->sentDidFinishLoad() && !frame->loader().provisionalDocumentLoader() && !frame->loader().client()->hasPendingNavigation();
}

void FrameLoader::checkCompleted()
{
    RefPtrWillBeRawPtr<LocalFrame> protect(m_frame.get());
    if (!shouldComplete(m_frame->document()))
        return;

    // OK, completed.
    m_frame->document()->setReadyState(Document::Complete);
    if (m_frame->document()->loadEventStillNeeded())
        m_frame->document()->implicitClose();

    m_frame->navigationScheduler().startTimer();

    if (m_frame->view())
        m_frame->view()->handleLoadCompleted();

    // The readystatechanged or load event may have disconnected this frame.
    if (!m_frame->client())
        return;

    if (shouldSendFinishNotification(m_frame)) {
        // Report mobile vs. desktop page statistics. This will only report on Android.
        if (m_frame->isMainFrame())
            m_frame->document()->viewportDescription().reportMobilePageStats(m_frame);
        m_documentLoader->setSentDidFinishLoad();
        client()->dispatchDidFinishLoad();
        // Finishing the load can detach the frame when running layout tests.
        if (!m_frame->client())
            return;
    }

    if (shouldSendCompleteNotification(m_frame)) {
        m_progressTracker->progressCompleted();
        // Retry restoring scroll offset since finishing loading disables content
        // size clamping.
        restoreScrollPositionAndViewState();

        m_loadType = FrameLoadTypeStandard;
        m_frame->localDOMWindow()->finishedLoading();
    }

    Frame* parent = m_frame->tree().parent();
    if (parent && parent->isLocalFrame())
        toLocalFrame(parent)->loader().checkCompleted();
}

void FrameLoader::checkTimerFired(Timer<FrameLoader>*)
{
    if (Page* page = m_frame->page()) {
        if (page->defersLoading())
            return;
    }
    checkCompleted();
}

void FrameLoader::scheduleCheckCompleted()
{
    if (!m_checkTimer.isActive())
        m_checkTimer.startOneShot(0, BLINK_FROM_HERE);
}

Frame* FrameLoader::opener()
{
    return client() ? client()->opener() : 0;
}

void FrameLoader::setOpener(LocalFrame* opener)
{
    // If the frame is already detached, the opener has already been cleared.
    if (client())
        client()->setOpener(opener);
}

bool FrameLoader::allowPlugins(ReasonForCallingAllowPlugins reason)
{
    // With Oilpan, a FrameLoader might be accessed after the
    // FrameHost has been detached. FrameClient will not be
    // accessible, so bail early.
    if (!client())
        return false;
    Settings* settings = m_frame->settings();
    bool allowed = client()->allowPlugins(settings && settings->pluginsEnabled());
    if (!allowed && reason == AboutToInstantiatePlugin)
        client()->didNotAllowPlugins();
    return allowed;
}

void FrameLoader::updateForSameDocumentNavigation(const KURL& newURL, SameDocumentNavigationSource sameDocumentNavigationSource, PassRefPtr<SerializedScriptValue> data, HistoryScrollRestorationType scrollRestorationType, 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())
        client()->didStartLoading(NavigationWithinSameDocument);

    HistoryCommitType historyCommitType = loadTypeToCommitType(type);
    if (!m_currentItem)
        historyCommitType = HistoryInertCommit;

    setHistoryItemStateForCommit(historyCommitType, sameDocumentNavigationSource == SameDocumentNavigationHistoryApi ? HistoryNavigationType::HistoryApi : HistoryNavigationType::Fragment);
    if (sameDocumentNavigationSource == SameDocumentNavigationHistoryApi) {
        m_currentItem->setStateObject(data);
        m_currentItem->setScrollRestorationType(scrollRestorationType);
    }
    client()->dispatchDidNavigateWithinPage(m_currentItem.get(), historyCommitType);
    client()->dispatchDidReceiveTitle(m_frame->document()->title());
    if (m_frame->document()->loadEventFinished())
        client()->didStopLoading();
}

void FrameLoader::detachDocumentLoader(RefPtrWillBeMember<DocumentLoader>& loader)
{
    if (!loader)
        return;

    loader->detachFromFrame();
    loader = nullptr;
}

void FrameLoader::loadInSameDocument(const KURL& url, PassRefPtr<SerializedScriptValue> stateObject, FrameLoadType frameLoadType, HistoryLoadType historyLoadType, ClientRedirectPolicy clientRedirect)
{
    // If we have a state object, we cannot also be a new navigation.
    ASSERT(!stateObject || frameLoadType == FrameLoadTypeBackForward);

    // If we have a provisional request for a different document, a fragment scroll should cancel it.
    if (m_provisionalDocumentLoader) {
        m_provisionalDocumentLoader->stopLoading();
        detachDocumentLoader(m_provisionalDocumentLoader);
        if (!m_frame->host())
            return;
    }
    TemporaryChange<FrameLoadType> loadTypeChange(m_loadType, frameLoadType);
    saveScrollState();

    KURL oldURL = m_frame->document()->url();
    bool hashChange = equalIgnoringFragmentIdentifier(url, oldURL) && url.fragmentIdentifier() != oldURL.fragmentIdentifier();
    if (hashChange) {
        // If we were in the autoscroll/panScroll mode we want to stop it before following the link to the anchor
        m_frame->eventHandler().stopAutoscroll();
        m_frame->localDOMWindow()->enqueueHashchangeEvent(oldURL, url);
    }
    m_documentLoader->setIsClientRedirect(clientRedirect == ClientRedirect);
    updateForSameDocumentNavigation(url, SameDocumentNavigationDefault, nullptr, ScrollRestorationAuto, frameLoadType);

    m_documentLoader->initialScrollState().wasScrolledByUser = false;

    checkCompleted();

    m_frame->localDOMWindow()->statePopped(stateObject ? stateObject : SerializedScriptValue::nullValue());

    if (historyLoadType == HistorySameDocumentLoad)
        restoreScrollPositionAndViewState();

    // We need to scroll to the fragment whether or not a hash change occurred, since
    // the user might have scrolled since the previous navigation.
    processFragment(url, NavigationWithinSameDocument);
}

void FrameLoader::setReferrerForFrameRequest(ResourceRequest& request, ShouldSendReferrer shouldSendReferrer, Document* originDocument)
{
    if (!originDocument)
        return;
    // Anchor elements with the 'referrerpolicy' attribute will have
    // already set the referrer on the request.
    if (request.didSetHTTPReferrer())
        return;
    if (shouldSendReferrer == NeverSendReferrer)
        return;

    // Always use the initiating document to generate the referrer.
    // We need to generateReferrer(), because we haven't enforced ReferrerPolicy or https->http
    // referrer suppression yet.
    Referrer referrer = SecurityPolicy::generateReferrer(originDocument->getReferrerPolicy(), request.url(), originDocument->outgoingReferrer());

    request.setHTTPReferrer(referrer);
    RefPtr<SecurityOrigin> referrerOrigin = SecurityOrigin::createFromString(referrer.referrer);
    request.addHTTPOriginIfNeeded(referrerOrigin);
}

FrameLoadType FrameLoader::determineFrameLoadType(const FrameLoadRequest& request)
{
    if (m_frame->tree().parent() && !m_stateMachine.committedFirstRealDocumentLoad())
        return FrameLoadTypeInitialInChildFrame;
    if (!m_frame->tree().parent() && !client()->backForwardLength())
        return FrameLoadTypeStandard;
    if (m_provisionalDocumentLoader && request.substituteData().failingURL() == m_provisionalDocumentLoader->url() && m_loadType == FrameLoadTypeBackForward)
        return FrameLoadTypeBackForward;
    if (request.resourceRequest().getCachePolicy() == ReloadIgnoringCacheData)
        return FrameLoadTypeReload;
    if (request.resourceRequest().getCachePolicy() == ReloadBypassingCache)
        return FrameLoadTypeReloadFromOrigin;
    // From the HTML5 spec for location.assign():
    //  "If the browsing context's session history contains only one Document,
    //   and that was the about:blank Document created when the browsing context
    //   was created, then the navigation must be done with replacement enabled."
    if (request.replacesCurrentItem()
        || (!m_stateMachine.committedMultipleRealLoads()
            && equalIgnoringCase(m_frame->document()->url(), blankURL())))
        return FrameLoadTypeReplaceCurrentItem;

    if (request.resourceRequest().url() == m_documentLoader->urlForHistory()) {
        if (!request.originDocument())
            return FrameLoadTypeSame;
        return request.resourceRequest().httpMethod() == HTTPNames::POST ? FrameLoadTypeStandard : FrameLoadTypeReplaceCurrentItem;
    }

    if (request.substituteData().failingURL() == m_documentLoader->urlForHistory() && m_loadType == FrameLoadTypeReload)
        return FrameLoadTypeReload;
    return FrameLoadTypeStandard;
}

bool FrameLoader::prepareRequestForThisFrame(FrameLoadRequest& request)
{
    // If no origin Document* was specified, skip remaining security checks and assume the caller has fully initialized the FrameLoadRequest.
    if (!request.originDocument())
        return true;

    KURL url = request.resourceRequest().url();
    if (m_frame->script().executeScriptIfJavaScriptURL(url))
        return false;

    if (!request.originDocument()->getSecurityOrigin()->canDisplay(url)) {
        reportLocalLoadFailed(m_frame, url.elidedString());
        return false;
    }

    if (!request.form() && request.frameName().isEmpty())
        request.setFrameName(m_frame->document()->baseTarget());
    return true;
}

static bool shouldOpenInNewWindow(Frame* targetFrame, const FrameLoadRequest& request, NavigationPolicy policy)
{
    if (!targetFrame && !request.frameName().isEmpty())
        return true;
    // FIXME: This case is a workaround for the fact that ctrl+clicking a form submission incorrectly
    // sends as a GET rather than a POST if it creates a new window in a different process.
    return request.form() && policy != NavigationPolicyCurrentTab;
}

static NavigationType determineNavigationType(FrameLoadType frameLoadType, bool isFormSubmission, bool haveEvent)
{
    bool isReload = frameLoadType == FrameLoadTypeReload || frameLoadType == FrameLoadTypeReloadFromOrigin;
    bool isBackForward = isBackForwardLoadType(frameLoadType);
    if (isFormSubmission)
        return (isReload || isBackForward) ? NavigationTypeFormResubmitted : NavigationTypeFormSubmitted;
    if (haveEvent)
        return NavigationTypeLinkClicked;
    if (isReload)
        return NavigationTypeReload;
    if (isBackForward)
        return NavigationTypeBackForward;
    return NavigationTypeOther;
}

static WebURLRequest::RequestContext determineRequestContextFromNavigationType(const NavigationType navigationType)
{
    switch (navigationType) {
    case NavigationTypeLinkClicked:
        return WebURLRequest::RequestContextHyperlink;

    case NavigationTypeOther:
        return WebURLRequest::RequestContextLocation;

    case NavigationTypeFormResubmitted:
    case NavigationTypeFormSubmitted:
        return WebURLRequest::RequestContextForm;

    case NavigationTypeBackForward:
    case NavigationTypeReload:
        return WebURLRequest::RequestContextInternal;
    }
    ASSERT_NOT_REACHED();
    return WebURLRequest::RequestContextHyperlink;
}

static NavigationPolicy navigationPolicyForRequest(const FrameLoadRequest& request)
{
    NavigationPolicy policy = NavigationPolicyCurrentTab;
    Event* event = request.triggeringEvent();
    if (!event)
        return policy;

    if (request.form() && event->underlyingEvent())
        event = event->underlyingEvent();

    if (event->isMouseEvent()) {
        MouseEvent* mouseEvent = toMouseEvent(event);
        navigationPolicyFromMouseEvent(mouseEvent->button(), mouseEvent->ctrlKey(), mouseEvent->shiftKey(), mouseEvent->altKey(), mouseEvent->metaKey(), &policy);
    } else if (event->isKeyboardEvent()) {
        // The click is simulated when triggering the keypress event.
        KeyboardEvent* keyEvent = toKeyboardEvent(event);
        navigationPolicyFromMouseEvent(0, keyEvent->ctrlKey(), keyEvent->shiftKey(), keyEvent->altKey(), keyEvent->metaKey(), &policy);
    } else if (event->isGestureEvent()) {
        // The click is simulated when triggering the gesture-tap event
        GestureEvent* gestureEvent = toGestureEvent(event);
        navigationPolicyFromMouseEvent(0, gestureEvent->ctrlKey(), gestureEvent->shiftKey(), gestureEvent->altKey(), gestureEvent->metaKey(), &policy);
    }
    return policy;
}

void FrameLoader::load(const FrameLoadRequest& passedRequest, FrameLoadType frameLoadType,
    HistoryItem* historyItem, HistoryLoadType historyLoadType)
{
    ASSERT(m_frame->document());

    RefPtrWillBeRawPtr<LocalFrame> protect(m_frame.get());

    if (m_inStopAllLoaders)
        return;

    if (m_frame->page()->defersLoading() && isBackForwardLoadType(frameLoadType)) {
        m_deferredHistoryLoad = DeferredHistoryLoad::create(passedRequest.resourceRequest(), historyItem, frameLoadType, historyLoadType);
        return;
    }

    FrameLoadRequest request(passedRequest);
    request.resourceRequest().setHasUserGesture(UserGestureIndicator::processingUserGesture());

    if (!prepareRequestForThisFrame(request))
        return;

    RefPtrWillBeRawPtr<Frame> targetFrame = request.form() ? nullptr : m_frame->findFrameForNavigation(AtomicString(request.frameName()), *m_frame);

    if (isBackForwardLoadType(frameLoadType)) {
        ASSERT(historyItem);
        m_provisionalItem = historyItem;
    }

    if (targetFrame && targetFrame.get() != m_frame) {
        bool wasInSamePage = targetFrame->page() == m_frame->page();

        request.setFrameName("_self");
        targetFrame->navigate(request);
        Page* page = targetFrame->page();
        if (!wasInSamePage && page)
            page->chromeClient().focus();
        return;
    }

    setReferrerForFrameRequest(request.resourceRequest(), request.getShouldSendReferrer(), request.originDocument());

    FrameLoadType newLoadType = (frameLoadType == FrameLoadTypeStandard) ?
        determineFrameLoadType(request) : frameLoadType;
    NavigationPolicy policy = navigationPolicyForRequest(request);
    if (shouldOpenInNewWindow(targetFrame.get(), request, policy)) {
        if (policy == NavigationPolicyDownload) {
            client()->loadURLExternally(request.resourceRequest(), NavigationPolicyDownload, String(), false);
        } else {
            request.resourceRequest().setFrameType(WebURLRequest::FrameTypeAuxiliary);
            createWindowForRequest(request, *m_frame, policy, request.getShouldSendReferrer(), request.getShouldSetOpener());
        }
        return;
    }

    const KURL& url = request.resourceRequest().url();
    bool sameDocumentHistoryNavigation =
        isBackForwardLoadType(newLoadType) && historyLoadType == HistorySameDocumentLoad;
    bool sameDocumentNavigation = policy == NavigationPolicyCurrentTab
        && shouldPerformFragmentNavigation(
            request.form(), request.resourceRequest().httpMethod(), newLoadType, url);

    // Perform same document navigation.
    if (sameDocumentHistoryNavigation || sameDocumentNavigation) {
        ASSERT(historyItem || !sameDocumentHistoryNavigation);
        RefPtr<SerializedScriptValue> stateObject = sameDocumentHistoryNavigation ?
            historyItem->stateObject() : nullptr;

        if (!sameDocumentHistoryNavigation) {
            m_documentLoader->setNavigationType(determineNavigationType(
                newLoadType, false, request.triggeringEvent()));
            if (shouldTreatURLAsSameAsCurrent(url))
                newLoadType = FrameLoadTypeReplaceCurrentItem;
        }

        loadInSameDocument(url, stateObject, newLoadType, historyLoadType, request.clientRedirect());
        return;
    }

    startLoad(request, newLoadType, policy);
}

SubstituteData FrameLoader::defaultSubstituteDataForURL(const KURL& url)
{
    if (!shouldTreatURLAsSrcdocDocument(url))
        return SubstituteData();
    String srcdoc = m_frame->deprecatedLocalOwner()->fastGetAttribute(srcdocAttr);
    ASSERT(!srcdoc.isNull());
    CString encodedSrcdoc = srcdoc.utf8();
    return SubstituteData(SharedBuffer::create(encodedSrcdoc.data(), encodedSrcdoc.length()), "text/html", "UTF-8", KURL());
}

void FrameLoader::reportLocalLoadFailed(LocalFrame* frame, const String& url)
{
    ASSERT(!url.isEmpty());
    if (!frame)
        return;

    frame->document()->addConsoleMessage(ConsoleMessage::create(SecurityMessageSource, ErrorMessageLevel, "Not allowed to load local resource: " + url));
}

void FrameLoader::stopAllLoaders()
{
    if (m_frame->document()->pageDismissalEventBeingDispatched() != Document::NoDismissal)
        return;

    // If this method is called from within this method, infinite recursion can occur (3442218). Avoid this.
    if (m_inStopAllLoaders)
        return;

    // Calling stopLoading() on the provisional document loader can blow away
    // the frame from underneath.
    RefPtrWillBeRawPtr<LocalFrame> protect(m_frame.get());

    m_inStopAllLoaders = true;

    for (RefPtrWillBeRawPtr<Frame> child = m_frame->tree().firstChild(); child; child = child->tree().nextSibling()) {
        if (child->isLocalFrame())
            toLocalFrame(child.get())->loader().stopAllLoaders();
    }

    m_frame->document()->suppressLoadEvent();
    // Don't stop loading the provisional loader if it is being protected (i.e.
    // it is about to be committed) See prepareForCommit() for more details.
    if (m_provisionalDocumentLoader && !m_protectProvisionalLoader)
        m_provisionalDocumentLoader->stopLoading();
    if (m_documentLoader)
        m_documentLoader->stopLoading();
    m_frame->document()->cancelParsing();

    if (!m_protectProvisionalLoader)
        detachDocumentLoader(m_provisionalDocumentLoader);

    m_checkTimer.stop();
    m_frame->navigationScheduler().cancel();

    m_inStopAllLoaders = false;
}

void FrameLoader::didAccessInitialDocument()
{
    // We only need to notify the client once, and only for the main frame.
    if (isLoadingMainFrame() && !m_didAccessInitialDocument) {
        m_didAccessInitialDocument = true;
        // Notify asynchronously, since this is called within a JavaScript security check.
        m_didAccessInitialDocumentTimer.startOneShot(0, BLINK_FROM_HERE);
    }
}

void FrameLoader::didAccessInitialDocumentTimerFired(Timer<FrameLoader>*)
{
    if (client())
        client()->didAccessInitialDocument();
}

void FrameLoader::notifyIfInitialDocumentAccessed()
{
    if (m_didAccessInitialDocumentTimer.isActive()) {
        m_didAccessInitialDocumentTimer.stop();
        didAccessInitialDocumentTimerFired(0);
    }
}

bool FrameLoader::prepareForCommit()
{
    PluginScriptForbiddenScope forbidPluginDestructorScripting;
    RefPtrWillBeRawPtr<DocumentLoader> pdl = m_provisionalDocumentLoader;

    if (m_frame->document()) {
        unsigned nodeCount = 0;
        for (Frame* frame = m_frame; frame; frame = frame->tree().traverseNext()) {
            if (frame->isLocalFrame()) {
                LocalFrame* localFrame = toLocalFrame(frame);
                nodeCount += localFrame->document()->nodeCount();
            }
        }
        unsigned totalNodeCount = InstanceCounters::counterValue(InstanceCounters::NodeCounter);
        float ratio = static_cast<float>(nodeCount) / totalNodeCount;
        ThreadState::current()->schedulePageNavigationGCIfNeeded(ratio);
    }

    // Don't allow any new child frames to load in this frame: attaching a new
    // child frame during or after detaching children results in an attached
    // frame on a detached DOM tree, which is bad.
    SubframeLoadingDisabler disabler(m_frame->document());
    if (m_documentLoader) {
        client()->dispatchWillClose();
        dispatchUnloadEvent();
    }
    m_frame->detachChildren();
    // The previous calls to dispatchUnloadEvent() and detachChildren() can
    // execute arbitrary script via things like unload events. If the executed
    // script intiates a new load or causes the current frame to be detached,
    // we need to abandon the current load.
    if (pdl != m_provisionalDocumentLoader)
        return false;
    // detachFromFrame() will abort XHRs that haven't completed, which can
    // trigger event listeners for 'abort'. These event listeners might call
    // window.stop(), which will in turn detach the provisional document loader.
    // At this point, the provisional document loader should not detach, because
    // then the FrameLoader would not have any attached DocumentLoaders.
    if (m_documentLoader) {
        FrameNavigationDisabler navigationDisabler(*m_frame);
        TemporaryChange<bool> inDetachDocumentLoader(m_protectProvisionalLoader, true);
        detachDocumentLoader(m_documentLoader);
    }
    // 'abort' listeners can also detach the frame.
    if (!m_frame->client())
        return false;
    ASSERT(m_provisionalDocumentLoader == pdl);
    // No more events will be dispatched so detach the Document.
    // TODO(yoav): Should we also be nullifying domWindow's document (or domWindow) since the doc is now detached?
    if (m_frame->document())
        m_frame->document()->detach();
    m_documentLoader = m_provisionalDocumentLoader.release();

    return true;
}

void FrameLoader::commitProvisionalLoad()
{
    ASSERT(client()->hasWebView());
    RefPtrWillBeRawPtr<LocalFrame> protect(m_frame.get());

    // Check if the destination page is allowed to access the previous page's timing information.
    if (m_frame->document()) {
        RefPtr<SecurityOrigin> securityOrigin = SecurityOrigin::create(m_provisionalDocumentLoader->request().url());
        m_provisionalDocumentLoader->timing().setHasSameOriginAsPreviousDocument(securityOrigin->canRequest(m_frame->document()->url()));
    }

    if (!prepareForCommit())
        return;

    if (isLoadingMainFrame()) {
        m_frame->page()->chromeClient().setEventListenerProperties(WebEventListenerClass::Touch, WebEventListenerProperties::Nothing);
        m_frame->page()->chromeClient().setEventListenerProperties(WebEventListenerClass::MouseWheel, WebEventListenerProperties::Nothing);
    }

    client()->transitionToCommittedForNewPage();
    m_frame->navigationScheduler().cancel();
    m_frame->editor().clearLastEditCommand();

    // If we are still in the process of initializing an empty document then
    // its frame is not in a consistent state for rendering, so avoid setJSStatusBarText
    // since it may cause clients to attempt to render the frame.
    if (!m_stateMachine.creatingInitialEmptyDocument()) {
        DOMWindow* window = m_frame->domWindow();
        window->setStatus(String());
        window->setDefaultStatus(String());
    }
}

bool FrameLoader::isLoadingMainFrame() const
{
    return m_frame->isMainFrame();
}

FrameLoadType FrameLoader::loadType() const
{
    return m_loadType;
}

void FrameLoader::restoreScrollPositionAndViewState()
{
    FrameView* view = m_frame->view();
    if (!m_frame->page()
        || !view
        || !view->layoutViewportScrollableArea()
        || !m_currentItem
        || !m_stateMachine.committedFirstRealDocumentLoad()
        || !documentLoader()) {
        return;
    }

    if (!needsHistoryItemRestore(m_loadType))
        return;

    bool shouldRestoreScroll = m_currentItem->scrollRestorationType() != ScrollRestorationManual;
    bool shouldRestoreScale = m_currentItem->pageScaleFactor();

    // This tries to balance:
    //   1. restoring as soon as possible
    //   2. not overriding user scroll (TODO(majidvp): also respect user scale)
    //   3. detecting clamping to avoid repeatedly popping the scroll position
    //      down as the page height increases
    //   4. ignore clamp detection if we are not restoring scroll or after load
    //      completes because that may be because the page will never reach its
    //      previous height
    bool canRestoreWithoutClamping = view->layoutViewportScrollableArea()->clampScrollPosition(m_currentItem->scrollPoint()) == m_currentItem->scrollPoint();
    bool canRestoreWithoutAnnoyingUser = !documentLoader()->initialScrollState().wasScrolledByUser
        && (canRestoreWithoutClamping || !m_frame->isLoading() || !shouldRestoreScroll);
    if (!canRestoreWithoutAnnoyingUser)
        return;

    if (shouldRestoreScroll)
        view->layoutViewportScrollableArea()->setScrollPosition(m_currentItem->scrollPoint(), ProgrammaticScroll);

    // For main frame restore scale and visual viewport position
    if (m_frame->isMainFrame()) {
        FloatPoint visualViewportOffset(m_currentItem->visualViewportScrollPoint());

        // If the visual viewport's offset is (-1, -1) it means the history item
        // is an old version of HistoryItem so distribute the scroll between
        // the main frame and the visual viewport as best as we can.
        if (visualViewportOffset.x() == -1 && visualViewportOffset.y() == -1)
            visualViewportOffset = FloatPoint(m_currentItem->scrollPoint() - view->scrollPosition());

        VisualViewport& visualViewport = m_frame->host()->visualViewport();
        if (shouldRestoreScale && shouldRestoreScroll)
            visualViewport.setScaleAndLocation(m_currentItem->pageScaleFactor(), visualViewportOffset);
        else if (shouldRestoreScale)
            visualViewport.setScale(m_currentItem->pageScaleFactor());
        else if (shouldRestoreScroll)
            visualViewport.setLocation(visualViewportOffset);

        if (ScrollingCoordinator* scrollingCoordinator = m_frame->page()->scrollingCoordinator())
            scrollingCoordinator->frameViewRootLayerDidChange(view);
    }

    documentLoader()->initialScrollState().didRestoreFromHistory = true;
}

String FrameLoader::userAgent() const
{
    String userAgent = client()->userAgent();
    InspectorInstrumentation::applyUserAgentOverride(m_frame, &userAgent);
    return userAgent;
}

void FrameLoader::detach()
{
#if !ENABLE(OILPAN)
    // The caller must protect a reference to m_frame.
    ASSERT(m_frame->refCount() > 1);
#endif
    detachDocumentLoader(m_documentLoader);
    detachDocumentLoader(m_provisionalDocumentLoader);

    Frame* parent = m_frame->tree().parent();
    if (parent && parent->isLocalFrame())
        toLocalFrame(parent)->loader().scheduleCheckCompleted();
    if (m_progressTracker) {
        m_progressTracker->dispose();
        m_progressTracker.clear();
    }
}

void FrameLoader::receivedMainResourceError(DocumentLoader* loader, const ResourceError& error)
{
    // Retain because the stop may release the last reference to it.
    RefPtrWillBeRawPtr<LocalFrame> protect(m_frame.get());
    RefPtrWillBeRawPtr<DocumentLoader> protectDocumentLoader(loader);

    // FIXME: We really ought to be able to just check for isCancellation() here, but there are some
    // ResourceErrors that setIsCancellation() but aren't created by ResourceError::cancelledError().
    ResourceError c(ResourceError::cancelledError(KURL()));
    if ((error.errorCode() != c.errorCode() || error.domain() != c.domain()) && 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) {
        client()->dispatchDidFailProvisionalLoad(error, historyCommitType);
        if (loader != m_provisionalDocumentLoader)
            return;
        detachDocumentLoader(m_provisionalDocumentLoader);
        m_progressTracker->progressCompleted();
    } else {
        ASSERT(loader == m_documentLoader);
        if (m_frame->document()->parser())
            m_frame->document()->parser()->stopParsing();
        m_documentLoader->setSentDidFinishLoad();
        if (!m_provisionalDocumentLoader && m_frame->isLoading()) {
            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", explicitly reloading,
    // currently displaying a frameset, or if the URL does not have a fragment.
    return (!isFormSubmission || equalIgnoringCase(httpMethod, HTTPNames::GET))
        && loadType != FrameLoadTypeReload
        && loadType != FrameLoadTypeReloadFromOrigin
        && loadType != FrameLoadTypeSame
        && loadType != FrameLoadTypeBackForward
        && url.hasFragmentIdentifier()
        && equalIgnoringFragmentIdentifier(m_frame->document()->url(), url)
        // We don't want to just scroll if a link from within a
        // frameset is trying to reload the frameset into _top.
        && !m_frame->document()->isFrameSet();
}

void FrameLoader::processFragment(const KURL& url, LoadStartType loadStartType)
{
    FrameView* view = m_frame->view();
    if (!view)
        return;

    // Leaking scroll position to a cross-origin ancestor would permit the so-called "framesniffing" attack.
    RefPtrWillBeRawPtr<Frame> boundaryFrame = url.hasFragmentIdentifier() ? m_frame->findUnsafeParentScrollPropagationBoundary() : 0;

    // FIXME: Handle RemoteFrames
    if (boundaryFrame && boundaryFrame->isLocalFrame())
        toLocalFrame(boundaryFrame.get())->view()->setSafeToPropagateScrollToParent(false);

    // If scroll position is restored from history fragment then we should not override it unless
    // this is a same document reload.
    bool shouldScrollToFragment = (loadStartType == NavigationWithinSameDocument && !isBackForwardLoadType(m_loadType))
        || (documentLoader() && !documentLoader()->initialScrollState().didRestoreFromHistory);

    view->processUrlFragment(url, shouldScrollToFragment ?
        FrameView::UrlFragmentScroll : FrameView::UrlFragmentDontScroll);

    if (boundaryFrame && boundaryFrame->isLocalFrame())
        toLocalFrame(boundaryFrame.get())->view()->setSafeToPropagateScrollToParent(true);
}

bool FrameLoader::shouldClose(bool isReload)
{
    Page* page = m_frame->page();
    if (!page || !page->chromeClient().canOpenBeforeUnloadConfirmPanel())
        return true;

    // Store all references to each subframe in advance since beforeunload's event handler may modify frame
    WillBeHeapVector<RefPtrWillBeMember<LocalFrame>> targetFrames;
    targetFrames.append(m_frame);
    for (Frame* child = m_frame->tree().firstChild(); child; child = child->tree().traverseNext(m_frame)) {
        // FIXME: There is not yet any way to dispatch events to out-of-process frames.
        if (child->isLocalFrame())
            targetFrames.append(toLocalFrame(child));
    }

    bool shouldClose = false;
    {
        NavigationDisablerForBeforeUnload navigationDisabler;
        size_t i;

        bool didAllowNavigation = false;
        for (i = 0; i < targetFrames.size(); i++) {
            if (!targetFrames[i]->tree().isDescendantOf(m_frame))
                continue;
            if (!targetFrames[i]->document()->dispatchBeforeUnloadEvent(page->chromeClient(), isReload, didAllowNavigation))
                break;
        }

        if (i == targetFrames.size())
            shouldClose = true;
    }
    return shouldClose;
}

bool FrameLoader::shouldContinueForNavigationPolicy(const ResourceRequest& request, const SubstituteData& substituteData,
    DocumentLoader* loader, ContentSecurityPolicyDisposition shouldCheckMainWorldContentSecurityPolicy,
    NavigationType type, NavigationPolicy policy, bool replacesCurrentHistoryItem, bool isClientRedirect)
{
    // Don't ask if we are loading an empty URL.
    if (request.url().isEmpty() || substituteData.isValid())
        return true;

    // If we're loading content into a subframe, check against the parent's Content Security Policy
    // and kill the load if that check fails, unless we should bypass the main world's CSP.
    // FIXME: CSP checks are broken for OOPI. For now, this policy always allows frames with a remote parent...
    if ((shouldCheckMainWorldContentSecurityPolicy == CheckContentSecurityPolicy) && (m_frame->deprecatedLocalOwner() && !m_frame->deprecatedLocalOwner()->document().contentSecurityPolicy()->allowChildFrameFromSource(request.url(), request.followedRedirect() ? ContentSecurityPolicy::DidRedirect : ContentSecurityPolicy::DidNotRedirect))) {
        // Fire a load event, as timing attacks would otherwise reveal that the
        // frame was blocked. This way, it looks like every other cross-origin
        // page load.
        m_frame->document()->enforceSandboxFlags(SandboxOrigin);
        m_frame->owner()->dispatchLoad();
        return false;
    }

    bool isFormSubmission = type == NavigationTypeFormSubmitted || type == NavigationTypeFormResubmitted;
    if (isFormSubmission && !m_frame->document()->contentSecurityPolicy()->allowFormAction(request.url()))
        return false;

    policy = client()->decidePolicyForNavigation(request, loader, type, policy, replacesCurrentHistoryItem, isClientRedirect);
    if (policy == NavigationPolicyCurrentTab)
        return true;
    if (policy == NavigationPolicyIgnore)
        return false;
    if (policy == NavigationPolicyHandledByClient) {
        // Mark the frame as loading since the embedder is handling the navigation.
        m_progressTracker->progressStarted();
        return false;
    }
    if (!LocalDOMWindow::allowPopUp(*m_frame) && !UserGestureIndicator::processingUserGesture())
        return false;
    client()->loadURLExternally(request, policy, String(), replacesCurrentHistoryItem);
    return false;
}

void FrameLoader::startLoad(FrameLoadRequest& frameLoadRequest, FrameLoadType type, NavigationPolicy navigationPolicy)
{
    ASSERT(client()->hasWebView());
    // Lots of things in this function can detach the LocalFrame (stopAllLoaders, beforeunload handlers, etc.), so protect the frame.
    RefPtrWillBeRawPtr<LocalFrame> protect(m_frame.get());
    if (m_frame->document()->pageDismissalEventBeingDispatched() != Document::NoDismissal)
        return;

    NavigationType navigationType = determineNavigationType(type, frameLoadRequest.resourceRequest().httpBody() || frameLoadRequest.form(), frameLoadRequest.triggeringEvent());
    frameLoadRequest.resourceRequest().setRequestContext(determineRequestContextFromNavigationType(navigationType));
    frameLoadRequest.resourceRequest().setFrameType(m_frame->isMainFrame() ? WebURLRequest::FrameTypeTopLevel : WebURLRequest::FrameTypeNested);
    ResourceRequest& request = frameLoadRequest.resourceRequest();
    if (!shouldContinueForNavigationPolicy(request, frameLoadRequest.substituteData(), nullptr, frameLoadRequest.shouldCheckMainWorldContentSecurityPolicy(), navigationType, navigationPolicy, type == FrameLoadTypeReplaceCurrentItem, frameLoadRequest.clientRedirect() == ClientRedirect))
        return;
    if (!shouldClose(navigationType == NavigationTypeReload))
        return;

    m_frame->document()->cancelParsing();

    if (m_provisionalDocumentLoader) {
        m_provisionalDocumentLoader->stopLoading();
        detachDocumentLoader(m_provisionalDocumentLoader);
    }

    // beforeunload fired above, and detaching a DocumentLoader can fire
    // events, which can detach this frame.
    if (!m_frame->host())
        return;

    m_provisionalDocumentLoader = client()->createDocumentLoader(m_frame, request, frameLoadRequest.substituteData().isValid() ? frameLoadRequest.substituteData() : defaultSubstituteDataForURL(request.url()));
    m_provisionalDocumentLoader->setNavigationType(navigationType);
    m_provisionalDocumentLoader->setReplacesCurrentHistoryItem(type == FrameLoadTypeReplaceCurrentItem);
    m_provisionalDocumentLoader->setIsClientRedirect(frameLoadRequest.clientRedirect() == ClientRedirect);

    InspectorInstrumentation::didStartProvisionalLoad(m_frame);

    m_frame->navigationScheduler().cancel();
    m_checkTimer.stop();

    m_loadType = type;

    if (frameLoadRequest.form())
        client()->dispatchWillSubmitForm(frameLoadRequest.form());

    m_progressTracker->progressStarted();
    if (m_provisionalDocumentLoader->isClientRedirect())
        m_provisionalDocumentLoader->appendRedirect(m_frame->document()->url());
    m_provisionalDocumentLoader->appendRedirect(m_provisionalDocumentLoader->request().url());
    double triggeringEventTime = frameLoadRequest.triggeringEvent() ? frameLoadRequest.triggeringEvent()->platformTimeStamp() : 0;
    client()->dispatchDidStartProvisionalLoad(triggeringEventTime);
    ASSERT(m_provisionalDocumentLoader);
    m_provisionalDocumentLoader->startLoadingMainResource();
}

void FrameLoader::applyUserAgent(ResourceRequest& request)
{
    String userAgent = this->userAgent();
    ASSERT(!userAgent.isNull());
    request.setHTTPUserAgent(AtomicString(userAgent));
}

bool FrameLoader::shouldInterruptLoadForXFrameOptions(const String& content, const KURL& url, unsigned long requestIdentifier)
{
    UseCounter::count(m_frame->domWindow()->document(), UseCounter::XFrameOptions);

    Frame* topFrame = m_frame->tree().top();
    if (m_frame == topFrame)
        return false;

    XFrameOptionsDisposition disposition = parseXFrameOptionsHeader(content);

    switch (disposition) {
    case XFrameOptionsSameOrigin: {
        UseCounter::count(m_frame->domWindow()->document(), UseCounter::XFrameOptionsSameOrigin);
        RefPtr<SecurityOrigin> origin = SecurityOrigin::create(url);
        // Out-of-process ancestors are always a different origin.
        if (!topFrame->isLocalFrame() || !origin->isSameSchemeHostPort(toLocalFrame(topFrame)->document()->getSecurityOrigin()))
            return true;
        for (Frame* frame = m_frame->tree().parent(); frame; frame = frame->tree().parent()) {
            if (!frame->isLocalFrame() || !origin->isSameSchemeHostPort(toLocalFrame(frame)->document()->getSecurityOrigin())) {
                UseCounter::count(m_frame->domWindow()->document(), UseCounter::XFrameOptionsSameOriginWithBadAncestorChain);
                break;
            }
        }
        return false;
    }
    case XFrameOptionsDeny:
        return true;
    case XFrameOptionsAllowAll:
        return false;
    case XFrameOptionsConflict: {
        RefPtrWillBeRawPtr<ConsoleMessage> consoleMessage = ConsoleMessage::create(JSMessageSource, ErrorMessageLevel, "Multiple 'X-Frame-Options' headers with conflicting values ('" + content + "') encountered when loading '" + url.elidedString() + "'. Falling back to 'DENY'.");
        consoleMessage->setRequestIdentifier(requestIdentifier);
        m_frame->document()->addConsoleMessage(consoleMessage.release());
        return true;
    }
    case XFrameOptionsInvalid: {
        RefPtrWillBeRawPtr<ConsoleMessage> consoleMessage = ConsoleMessage::create(JSMessageSource, ErrorMessageLevel, "Invalid 'X-Frame-Options' header encountered when loading '" + url.elidedString() + "': '" + content + "' is not a recognized directive. The header will be ignored.");
        consoleMessage->setRequestIdentifier(requestIdentifier);
        m_frame->document()->addConsoleMessage(consoleMessage.release());
        return false;
    }
    default:
        ASSERT_NOT_REACHED();
        return false;
    }
}

bool FrameLoader::shouldTreatURLAsSameAsCurrent(const KURL& url) const
{
    return m_currentItem && url == m_currentItem->url();
}

bool FrameLoader::shouldTreatURLAsSrcdocDocument(const KURL& url) const
{
    if (!url.isAboutSrcdocURL())
        return false;
    HTMLFrameOwnerElement* ownerElement = m_frame->deprecatedLocalOwner();
    if (!isHTMLIFrameElement(ownerElement))
        return false;
    return ownerElement->fastHasAttribute(srcdocAttr);
}

void FrameLoader::dispatchDocumentElementAvailable()
{
    ScriptForbiddenScope forbidScripts;
    client()->documentElementAvailable();
}

void FrameLoader::runScriptsAtDocumentElementAvailable()
{
    client()->runScriptsAtDocumentElementAvailable();
    // The frame might be detached at this point.
}

void FrameLoader::dispatchDidClearDocumentOfWindowObject()
{
    if (!m_frame->script().canExecuteScripts(NotAboutToExecuteScript))
        return;

    InspectorInstrumentation::didClearDocumentOfWindowObject(m_frame);

    if (m_dispatchingDidClearWindowObjectInMainWorld)
        return;
    TemporaryChange<bool>
        inDidClearWindowObject(m_dispatchingDidClearWindowObjectInMainWorld, true);
    // We just cleared the document, not the entire window object, but for the
    // embedder that's close enough.
    client()->dispatchDidClearWindowObjectInMainWorld();
}

void FrameLoader::dispatchDidClearWindowObjectInMainWorld()
{
    if (!m_frame->script().canExecuteScripts(NotAboutToExecuteScript))
        return;

    if (m_dispatchingDidClearWindowObjectInMainWorld)
        return;
    TemporaryChange<bool>
        inDidClearWindowObject(m_dispatchingDidClearWindowObjectInMainWorld, true);
    client()->dispatchDidClearWindowObjectInMainWorld();
}

SandboxFlags FrameLoader::effectiveSandboxFlags() const
{
    SandboxFlags flags = m_forcedSandboxFlags;
    if (FrameOwner* frameOwner = m_frame->owner())
        flags |= frameOwner->getSandboxFlags();
    // Frames need to inherit the sandbox flags of their parent frame.
    if (Frame* parentFrame = m_frame->tree().parent())
        flags |= parentFrame->securityContext()->getSandboxFlags();
    return flags;
}

bool FrameLoader::shouldEnforceStrictMixedContentChecking() const
{
    Frame* parentFrame = m_frame->tree().parent();
    if (!parentFrame)
        return false;

    return parentFrame->securityContext()->shouldEnforceStrictMixedContentChecking();
}

SecurityContext::InsecureRequestsPolicy FrameLoader::getInsecureRequestsPolicy() const
{
    Frame* parentFrame = m_frame->tree().parent();
    if (!parentFrame)
        return SecurityContext::InsecureRequestsDoNotUpgrade;

    // 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 SecurityContext::InsecureRequestsDoNotUpgrade;

    ASSERT(toLocalFrame(parentFrame)->document());
    return toLocalFrame(parentFrame)->document()->getInsecureRequestsPolicy();
}

SecurityContext::InsecureNavigationsSet* FrameLoader::insecureNavigationsToUpgrade() const
{
    ASSERT(m_frame);
    Frame* parentFrame = m_frame->tree().parent();
    if (!parentFrame)
        return nullptr;

    // 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;

    ASSERT(toLocalFrame(parentFrame)->document());
    return toLocalFrame(parentFrame)->document()->insecureNavigationsToUpgrade();
}

} // namespace blink