Source/WebCore/page/Frame.cpp

/*
 * Copyright (C) 1998, 1999 Torben Weis <weis@kde.org>
 *                     1999 Lars Knoll <knoll@kde.org>
 *                     1999 Antti Koivisto <koivisto@kde.org>
 *                     2000 Simon Hausmann <hausmann@kde.org>
 *                     2000 Stefan Schimanski <1Stein@gmx.de>
 *                     2001 George Staikos <staikos@kde.org>
 * Copyright (C) 2004-2019 Apple Inc. All rights reserved.
 * Copyright (C) 2005 Alexey Proskuryakov <ap@nypop.com>
 * Copyright (C) 2008 Nokia Corporation and/or its subsidiary(-ies)
 * Copyright (C) 2008 Eric Seidel <eric@webkit.org>
 * Copyright (C) 2008 Google Inc.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public License
 * along with this library; see the file COPYING.LIB.  If not, write to
 * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
 * Boston, MA 02110-1301, USA.
 */

#include "config.h"
#include "Frame.h"

#include "ApplyStyleCommand.h"
#include "BackForwardCache.h"
#include "BackForwardController.h"
#include "CSSAnimationController.h"
#include "CSSComputedStyleDeclaration.h"
#include "CSSPropertyNames.h"
#include "CachedCSSStyleSheet.h"
#include "CachedResourceLoader.h"
#include "Chrome.h"
#include "ChromeClient.h"
#include "DOMWindow.h"
#include "DocumentTimeline.h"
#include "DocumentType.h"
#include "Editing.h"
#include "Editor.h"
#include "EditorClient.h"
#include "Event.h"
#include "EventHandler.h"
#include "EventNames.h"
#include "FloatQuad.h"
#include "FocusController.h"
#include "FrameDestructionObserver.h"
#include "FrameLoader.h"
#include "FrameLoaderClient.h"
#include "FrameSelection.h"
#include "FrameView.h"
#include "GraphicsContext.h"
#include "GraphicsLayer.h"
#include "HTMLFormControlElement.h"
#include "HTMLFormElement.h"
#include "HTMLFrameElementBase.h"
#include "HTMLNames.h"
#include "HTMLTableCellElement.h"
#include "HTMLTableRowElement.h"
#include "HitTestResult.h"
#include "ImageBuffer.h"
#include "InspectorInstrumentation.h"
#include "JSWindowProxy.h"
#include "Logging.h"
#include "NavigationScheduler.h"
#include "Navigator.h"
#include "NodeList.h"
#include "NodeTraversal.h"
#include "Page.h"
#include "ProcessWarming.h"
#include "RenderLayerCompositor.h"
#include "RenderTableCell.h"
#include "RenderText.h"
#include "RenderTextControl.h"
#include "RenderTheme.h"
#include "RenderView.h"
#include "RenderWidget.h"
#include "RuntimeEnabledFeatures.h"
#include "SVGDocument.h"
#include "SVGDocumentExtensions.h"
#include "ScriptController.h"
#include "ScriptSourceCode.h"
#include "ScrollingCoordinator.h"
#include "Settings.h"
#include "StyleProperties.h"
#include "StyleScope.h"
#include "TextNodeTraversal.h"
#include "TextResourceDecoder.h"
#include "UserContentController.h"
#include "UserContentURLPattern.h"
#include "UserGestureIndicator.h"
#include "UserScript.h"
#include "UserTypingGestureIndicator.h"
#include "VisibleUnits.h"
#include "markup.h"
#include "npruntime_impl.h"
#include "runtime_root.h"
#include <JavaScriptCore/RegularExpression.h>
#include <wtf/RefCountedLeakCounter.h>
#include <wtf/StdLibExtras.h>
#include <wtf/text/StringBuilder.h>

namespace WebCore {

using namespace HTMLNames;

#if PLATFORM(IOS_FAMILY)
static const Seconds scrollFrequency { 1000_s / 60. };
#endif

DEFINE_DEBUG_ONLY_GLOBAL(WTF::RefCountedLeakCounter, frameCounter, ("Frame"));

// We prewarm local storage for at most 5 origins in a given page.
static const unsigned maxlocalStoragePrewarmingCount { 5 };

static inline Frame* parentFromOwnerElement(HTMLFrameOwnerElement* ownerElement)
{
    if (!ownerElement)
        return 0;
    return ownerElement->document().frame();
}

static inline float parentPageZoomFactor(Frame* frame)
{
    Frame* parent = frame->tree().parent();
    if (!parent)
        return 1;
    return parent->pageZoomFactor();
}

static inline float parentTextZoomFactor(Frame* frame)
{
    Frame* parent = frame->tree().parent();
    if (!parent)
        return 1;
    return parent->textZoomFactor();
}

Frame::Frame(Page& page, HTMLFrameOwnerElement* ownerElement, FrameLoaderClient& frameLoaderClient)
    : m_mainFrame(ownerElement ? page.mainFrame() : *this)
    , m_page(&page)
    , m_settings(&page.settings())
    , m_treeNode(*this, parentFromOwnerElement(ownerElement))
    , m_loader(makeUniqueRef<FrameLoader>(*this, frameLoaderClient))
    , m_navigationScheduler(makeUniqueRef<NavigationScheduler>(*this))
    , m_ownerElement(ownerElement)
    , m_script(makeUniqueRef<ScriptController>(*this))
    , m_editor(makeUniqueRef<Editor>(*this))
    , m_selection(makeUniqueRef<FrameSelection>(this))
    , m_animationController(makeUniqueRef<CSSAnimationController>(*this))
    , m_pageZoomFactor(parentPageZoomFactor(this))
    , m_textZoomFactor(parentTextZoomFactor(this))
    , m_eventHandler(makeUniqueRef<EventHandler>(*this))
{
    ProcessWarming::initializeNames();

    if (ownerElement) {
        m_mainFrame.selfOnlyRef();
        page.incrementSubframeCount();
        ownerElement->setContentFrame(this);
    }

#ifndef NDEBUG
    frameCounter.increment();
#endif

    // Pause future ActiveDOMObjects if this frame is being created while the page is in a paused state.
    Frame* parent = parentFromOwnerElement(ownerElement);
    if (parent && parent->activeDOMObjectsAndAnimationsSuspended())
        suspendActiveDOMObjectsAndAnimations();
}

void Frame::init()
{
    m_loader->init();
}

Ref<Frame> Frame::create(Page* page, HTMLFrameOwnerElement* ownerElement, FrameLoaderClient* client)
{
    ASSERT(page);
    ASSERT(client);
    return adoptRef(*new Frame(*page, ownerElement, *client));
}

Frame::~Frame()
{
    setView(nullptr);
    loader().cancelAndClear();

    // FIXME: We should not be doing all this work inside the destructor

#ifndef NDEBUG
    frameCounter.decrement();
#endif

    disconnectOwnerElement();

    while (auto* destructionObserver = m_destructionObservers.takeAny())
        destructionObserver->frameDestroyed();

    if (!isMainFrame())
        m_mainFrame.selfOnlyDeref();
}

void Frame::addDestructionObserver(FrameDestructionObserver* observer)
{
    m_destructionObservers.add(observer);
}

void Frame::removeDestructionObserver(FrameDestructionObserver* observer)
{
    m_destructionObservers.remove(observer);
}

void Frame::setView(RefPtr<FrameView>&& view)
{
    // We the custom scroll bars as early as possible to prevent m_doc->detach()
    // from messing with the view such that its scroll bars won't be torn down.
    // FIXME: We should revisit this.
    if (m_view)
        m_view->prepareForDetach();

    // Prepare for destruction now, so any unload event handlers get run and the DOMWindow is
    // notified. If we wait until the view is destroyed, then things won't be hooked up enough for
    // these calls to work.
    if (!view && m_doc && m_doc->backForwardCacheState() != Document::InBackForwardCache)
        m_doc->prepareForDestruction();
    
    if (m_view)
        m_view->layoutContext().unscheduleLayout();
    
    m_eventHandler->clear();

    RELEASE_ASSERT(!m_doc || !m_doc->hasLivingRenderTree());

    m_view = WTFMove(view);
    
    // Only one form submission is allowed per view of a part.
    // Since this part may be getting reused as a result of being
    // pulled from the back/forward cache, reset this flag.
    loader().resetMultipleFormSubmissionProtection();
}

void Frame::setDocument(RefPtr<Document>&& newDocument)
{
    ASSERT(!newDocument || newDocument->frame() == this);

    if (m_documentIsBeingReplaced)
        return;

    m_documentIsBeingReplaced = true;

    if (isMainFrame()) {
        if (m_page)
            m_page->didChangeMainDocument();
        m_loader->client().dispatchDidChangeMainDocument();

        // We want to generate the same unique names whenever a page is loaded to avoid making layout tests
        // flaky and for things like form state restoration to work. To achieve this, we reset our frame
        // identifier generator every time the page is navigated.
        tree().resetFrameIdentifiers();
    }

#if ENABLE(ATTACHMENT_ELEMENT)
    if (m_doc) {
        for (auto& attachment : m_doc->attachmentElementsByIdentifier().values())
            editor().didRemoveAttachmentElement(attachment);
    }
#endif

    if (m_doc && m_doc->backForwardCacheState() != Document::InBackForwardCache)
        m_doc->prepareForDestruction();

    m_doc = newDocument.copyRef();
    ASSERT(!m_doc || m_doc->domWindow());
    ASSERT(!m_doc || m_doc->domWindow()->frame() == this);

    // Don't use m_doc because it can be overwritten and we want to guarantee
    // that the document is not destroyed during this function call.
    if (newDocument)
        newDocument->didBecomeCurrentDocumentInFrame();

#if ENABLE(ATTACHMENT_ELEMENT)
    if (m_doc) {
        for (auto& attachment : m_doc->attachmentElementsByIdentifier().values())
            editor().didInsertAttachmentElement(attachment);
    }
#endif

    InspectorInstrumentation::frameDocumentUpdated(*this);

    m_documentIsBeingReplaced = false;
}

#if ENABLE(ORIENTATION_EVENTS)
void Frame::orientationChanged()
{
    Vector<Ref<Frame>> frames;
    for (Frame* frame = this; frame; frame = frame->tree().traverseNext())
        frames.append(*frame);

    auto newOrientation = orientation();
    for (auto& frame : frames) {
        if (Document* document = frame->document())
            document->orientationChanged(newOrientation);
    }
}

int Frame::orientation() const
{
    if (m_page)
        return m_page->chrome().client().deviceOrientation();
    return 0;
}
#endif // ENABLE(ORIENTATION_EVENTS)

static JSC::Yarr::RegularExpression createRegExpForLabels(const Vector<String>& labels)
{
    // REVIEW- version of this call in FrameMac.mm caches based on the NSArray ptrs being
    // the same across calls.  We can't do that.

    static NeverDestroyed<JSC::Yarr::RegularExpression> wordRegExp("\\w");
    StringBuilder pattern;
    pattern.append('(');
    unsigned int numLabels = labels.size();
    unsigned int i;
    for (i = 0; i < numLabels; i++) {
        String label = labels[i];

        bool startsWithWordChar = false;
        bool endsWithWordChar = false;
        if (label.length()) {
            startsWithWordChar = wordRegExp.get().match(label.substring(0, 1)) >= 0;
            endsWithWordChar = wordRegExp.get().match(label.substring(label.length() - 1, 1)) >= 0;
        }

        if (i)
            pattern.append('|');
        // Search for word boundaries only if label starts/ends with "word characters".
        // If we always searched for word boundaries, this wouldn't work for languages
        // such as Japanese.
        if (startsWithWordChar)
            pattern.appendLiteral("\\b");
        pattern.append(label);
        if (endsWithWordChar)
            pattern.appendLiteral("\\b");
    }
    pattern.append(')');
    return JSC::Yarr::RegularExpression(pattern.toString(), JSC::Yarr::TextCaseInsensitive);
}

String Frame::searchForLabelsAboveCell(const JSC::Yarr::RegularExpression& regExp, HTMLTableCellElement* cell, size_t* resultDistanceFromStartOfCell)
{
    HTMLTableCellElement* aboveCell = cell->cellAbove();
    if (aboveCell) {
        // search within the above cell we found for a match
        size_t lengthSearched = 0;    
        for (Text* textNode = TextNodeTraversal::firstWithin(*aboveCell); textNode; textNode = TextNodeTraversal::next(*textNode, aboveCell)) {
            if (!textNode->renderer() || textNode->renderer()->style().visibility() != Visibility::Visible)
                continue;
            // For each text chunk, run the regexp
            String nodeString = textNode->data();
            int pos = regExp.searchRev(nodeString);
            if (pos >= 0) {
                if (resultDistanceFromStartOfCell)
                    *resultDistanceFromStartOfCell = lengthSearched;
                return nodeString.substring(pos, regExp.matchedLength());
            }
            lengthSearched += nodeString.length();
        }
    }

    // Any reason in practice to search all cells in that are above cell?
    if (resultDistanceFromStartOfCell)
        *resultDistanceFromStartOfCell = notFound;
    return String();
}

// FIXME: This should take an Element&.
String Frame::searchForLabelsBeforeElement(const Vector<String>& labels, Element* element, size_t* resultDistance, bool* resultIsInCellAbove)
{
    ASSERT(element);
    JSC::Yarr::RegularExpression regExp = createRegExpForLabels(labels);
    // We stop searching after we've seen this many chars
    const unsigned int charsSearchedThreshold = 500;
    // This is the absolute max we search.  We allow a little more slop than
    // charsSearchedThreshold, to make it more likely that we'll search whole nodes.
    const unsigned int maxCharsSearched = 600;
    // If the starting element is within a table, the cell that contains it
    HTMLTableCellElement* startingTableCell = nullptr;
    bool searchedCellAbove = false;

    if (resultDistance)
        *resultDistance = notFound;
    if (resultIsInCellAbove)
        *resultIsInCellAbove = false;
    
    // walk backwards in the node tree, until another element, or form, or end of tree
    int unsigned lengthSearched = 0;
    Node* n;
    for (n = NodeTraversal::previous(*element); n && lengthSearched < charsSearchedThreshold; n = NodeTraversal::previous(*n)) {
        // We hit another form element or the start of the form - bail out
        if (is<HTMLFormElement>(*n) || is<HTMLFormControlElement>(*n))
            break;

        if (n->hasTagName(tdTag) && !startingTableCell)
            startingTableCell = downcast<HTMLTableCellElement>(n);
        else if (is<HTMLTableRowElement>(*n) && startingTableCell) {
            String result = searchForLabelsAboveCell(regExp, startingTableCell, resultDistance);
            if (!result.isEmpty()) {
                if (resultIsInCellAbove)
                    *resultIsInCellAbove = true;
                return result;
            }
            searchedCellAbove = true;
        } else if (n->isTextNode() && n->renderer() && n->renderer()->style().visibility() == Visibility::Visible) {
            // For each text chunk, run the regexp
            String nodeString = n->nodeValue();
            // add 100 for slop, to make it more likely that we'll search whole nodes
            if (lengthSearched + nodeString.length() > maxCharsSearched)
                nodeString = nodeString.right(charsSearchedThreshold - lengthSearched);
            int pos = regExp.searchRev(nodeString);
            if (pos >= 0) {
                if (resultDistance)
                    *resultDistance = lengthSearched;
                return nodeString.substring(pos, regExp.matchedLength());
            }
            lengthSearched += nodeString.length();
        }
    }

    // If we started in a cell, but bailed because we found the start of the form or the
    // previous element, we still might need to search the row above us for a label.
    if (startingTableCell && !searchedCellAbove) {
        String result = searchForLabelsAboveCell(regExp, startingTableCell, resultDistance);
        if (!result.isEmpty()) {
            if (resultIsInCellAbove)
                *resultIsInCellAbove = true;
            return result;
        }
    }
    return String();
}

static String matchLabelsAgainstString(const Vector<String>& labels, const String& stringToMatch)
{
    if (stringToMatch.isEmpty())
        return String();

    String mutableStringToMatch = stringToMatch;

    // Make numbers and _'s in field names behave like word boundaries, e.g., "address2"
    replace(mutableStringToMatch, JSC::Yarr::RegularExpression("\\d"), " ");
    mutableStringToMatch.replace('_', ' ');
    
    JSC::Yarr::RegularExpression regExp = createRegExpForLabels(labels);
    // Use the largest match we can find in the whole string
    int pos;
    int length;
    int bestPos = -1;
    int bestLength = -1;
    int start = 0;
    do {
        pos = regExp.match(mutableStringToMatch, start);
        if (pos != -1) {
            length = regExp.matchedLength();
            if (length >= bestLength) {
                bestPos = pos;
                bestLength = length;
            }
            start = pos + 1;
        }
    } while (pos != -1);
    
    if (bestPos != -1)
        return mutableStringToMatch.substring(bestPos, bestLength);
    return String();
}
    
String Frame::matchLabelsAgainstElement(const Vector<String>& labels, Element* element)
{
    // Match against the name element, then against the id element if no match is found for the name element.
    // See 7538330 for one popular site that benefits from the id element check.
    // FIXME: This code is mirrored in FrameMac.mm. It would be nice to make the Mac code call the platform-agnostic
    // code, which would require converting the NSArray of NSStrings to a Vector of Strings somewhere along the way.
    String resultFromNameAttribute = matchLabelsAgainstString(labels, element->getNameAttribute());
    if (!resultFromNameAttribute.isEmpty())
        return resultFromNameAttribute;
    
    return matchLabelsAgainstString(labels, element->attributeWithoutSynchronization(idAttr));
}

#if PLATFORM(IOS_FAMILY)

void Frame::setSelectionChangeCallbacksDisabled(bool selectionChangeCallbacksDisabled)
{
    m_selectionChangeCallbacksDisabled = selectionChangeCallbacksDisabled;
}

bool Frame::selectionChangeCallbacksDisabled() const
{
    return m_selectionChangeCallbacksDisabled;
}
#endif // PLATFORM(IOS_FAMILY)

bool Frame::requestDOMPasteAccess()
{
    if (m_settings->javaScriptCanAccessClipboard() && m_settings->DOMPasteAllowed())
        return true;

    if (!m_settings->domPasteAccessRequestsEnabled() || !m_doc)
        return false;

    auto gestureToken = UserGestureIndicator::currentUserGesture();
    if (!gestureToken || !gestureToken->processingUserGesture())
        return false;

    switch (gestureToken->domPasteAccessPolicy()) {
    case DOMPasteAccessPolicy::Granted:
        return true;
    case DOMPasteAccessPolicy::Denied:
        return false;
    case DOMPasteAccessPolicy::NotRequestedYet: {
        auto* client = m_editor->client();
        if (!client)
            return false;

        auto response = client->requestDOMPasteAccess(m_doc->originIdentifierForPasteboard());
        gestureToken->didRequestDOMPasteAccess(response);
        switch (response) {
        case DOMPasteAccessResponse::GrantedForCommand:
        case DOMPasteAccessResponse::GrantedForGesture:
            return true;
        case DOMPasteAccessResponse::DeniedForGesture:
            return false;
        }
    }
    }

    ASSERT_NOT_REACHED();
    return false;
}

void Frame::setPrinting(bool printing, const FloatSize& pageSize, const FloatSize& originalPageSize, float maximumShrinkRatio, AdjustViewSizeOrNot shouldAdjustViewSize)
{
    if (!view())
        return;
    // In setting printing, we should not validate resources already cached for the document.
    // See https://bugs.webkit.org/show_bug.cgi?id=43704
    ResourceCacheValidationSuppressor validationSuppressor(m_doc->cachedResourceLoader());

    m_doc->setPrinting(printing);
    auto& frameView = *view();
    frameView.adjustMediaTypeForPrinting(printing);

    // FIXME: Consider invoking Page::updateRendering or an equivalent.
    m_doc->styleScope().didChangeStyleSheetEnvironment();
    m_doc->evaluateMediaQueriesAndReportChanges();
    if (shouldUsePrintingLayout())
        frameView.forceLayoutForPagination(pageSize, originalPageSize, maximumShrinkRatio, shouldAdjustViewSize);
    else {
        frameView.forceLayout();
        if (shouldAdjustViewSize == AdjustViewSize)
            frameView.adjustViewSize();
    }

    // Subframes of the one we're printing don't lay out to the page size.
    for (RefPtr<Frame> child = tree().firstChild(); child; child = child->tree().nextSibling())
        child->setPrinting(printing, FloatSize(), FloatSize(), 0, shouldAdjustViewSize);
}

bool Frame::shouldUsePrintingLayout() const
{
    // Only top frame being printed should be fit to page size.
    // Subframes should be constrained by parents only.
    return m_doc->printing() && (!tree().parent() || !tree().parent()->m_doc->printing());
}

FloatSize Frame::resizePageRectsKeepingRatio(const FloatSize& originalSize, const FloatSize& expectedSize)
{
    FloatSize resultSize;
    if (!contentRenderer())
        return FloatSize();

    if (contentRenderer()->style().isHorizontalWritingMode()) {
        ASSERT(fabs(originalSize.width()) > std::numeric_limits<float>::epsilon());
        float ratio = originalSize.height() / originalSize.width();
        resultSize.setWidth(floorf(expectedSize.width()));
        resultSize.setHeight(floorf(resultSize.width() * ratio));
    } else {
        ASSERT(fabs(originalSize.height()) > std::numeric_limits<float>::epsilon());
        float ratio = originalSize.width() / originalSize.height();
        resultSize.setHeight(floorf(expectedSize.height()));
        resultSize.setWidth(floorf(resultSize.height() * ratio));
    }
    return resultSize;
}

void Frame::injectUserScripts(UserScriptInjectionTime injectionTime)
{
    if (!m_page)
        return;

    if (loader().stateMachine().creatingInitialEmptyDocument() && !settings().shouldInjectUserScriptsInInitialEmptyDocument())
        return;

    m_page->userContentProvider().forEachUserScript([this, protectedThis = makeRef(*this), injectionTime](DOMWrapperWorld& world, const UserScript& script) {
        if (script.injectionTime() == injectionTime)
            injectUserScriptImmediately(world, script);
    });
}

void Frame::injectUserScriptImmediately(DOMWrapperWorld& world, const UserScript& script)
{
    auto* document = this->document();
    if (!document)
        return;
    if (script.injectedFrames() == InjectInTopFrameOnly && !isMainFrame())
        return;
    if (!UserContentURLPattern::matchesPatterns(document->url(), script.whitelist(), script.blacklist()))
        return;
    if (!m_script->shouldAllowUserAgentScripts(*document))
        return;

    document->setAsRunningUserScripts();
    loader().client().willInjectUserScript(world);
    m_script->evaluateInWorld(ScriptSourceCode(script.source(), URL(script.url())), world);
}

RenderView* Frame::contentRenderer() const
{
    return document() ? document()->renderView() : nullptr;
}

RenderWidget* Frame::ownerRenderer() const
{
    auto* ownerElement = m_ownerElement;
    if (!ownerElement)
        return nullptr;
    auto* object = ownerElement->renderer();
    // FIXME: If <object> is ever fixed to disassociate itself from frames
    // that it has started but canceled, then this can turn into an ASSERT
    // since m_ownerElement would be nullptr when the load is canceled.
    // https://bugs.webkit.org/show_bug.cgi?id=18585
    if (!is<RenderWidget>(object))
        return nullptr;
    return downcast<RenderWidget>(object);
}

Frame* Frame::frameForWidget(const Widget& widget)
{
    if (auto* renderer = RenderWidget::find(widget))
        return renderer->frameOwnerElement().document().frame();

    // Assume all widgets are either a FrameView or owned by a RenderWidget.
    // FIXME: That assumption is not right for scroll bars!
    return &downcast<FrameView>(widget).frame();
}

void Frame::clearTimers(FrameView *view, Document *document)
{
    if (view) {
        view->layoutContext().unscheduleLayout();
        if (RuntimeEnabledFeatures::sharedFeatures().webAnimationsCSSIntegrationEnabled()) {
            if (auto* timeline = document->existingTimeline())
                timeline->suspendAnimations();
        } else
            view->frame().animation().suspendAnimationsForDocument(document);
        view->frame().eventHandler().stopAutoscrollTimer();
    }
}

void Frame::clearTimers()
{
    clearTimers(m_view.get(), document());
}

void Frame::willDetachPage()
{
    if (Frame* parent = tree().parent())
        parent->loader().checkLoadComplete();

    for (auto& observer : m_destructionObservers)
        observer->willDetachPage();

    // FIXME: It's unclear as to why this is called more than once, but it is,
    // so page() could be NULL.
    if (page() && page()->focusController().focusedFrame() == this)
        page()->focusController().setFocusedFrame(nullptr);

    if (page() && page()->scrollingCoordinator() && m_view)
        page()->scrollingCoordinator()->willDestroyScrollableArea(*m_view);

    script().clearScriptObjects();
    script().updatePlatformScriptObjects();

    // We promise that the Frame is always connected to a Page while the render tree is live.
    //
    // The render tree can be torn down in a few different ways, but the two important ones are:
    //
    // - When calling Frame::setView() with a null FrameView*. This is always done before calling
    //   Frame::willDetachPage (this function.) Hence the assertion below.
    //
    // - When adding a document to the back/forward cache, the tree is torn down before instantiating
    //   the CachedPage+CachedFrame object tree.
    ASSERT(!document() || !document()->renderView());
}

void Frame::disconnectOwnerElement()
{
    if (m_ownerElement) {
        m_ownerElement->clearContentFrame();
        if (m_page)
            m_page->decrementSubframeCount();
    }
    m_ownerElement = nullptr;

    if (auto* document = this->document())
        document->frameWasDisconnectedFromOwner();
}

String Frame::displayStringModifiedByEncoding(const String& str) const
{
    return document() ? document()->displayStringModifiedByEncoding(str) : str;
}

VisiblePosition Frame::visiblePositionForPoint(const IntPoint& framePoint) const
{
    HitTestResult result = eventHandler().hitTestResultAtPoint(framePoint, HitTestRequest::ReadOnly | HitTestRequest::Active | HitTestRequest::AllowChildFrameContent);
    Node* node = result.innerNonSharedNode();
    if (!node)
        return VisiblePosition();
    auto renderer = node->renderer();
    if (!renderer)
        return VisiblePosition();
    VisiblePosition visiblePos = renderer->positionForPoint(result.localPoint(), nullptr);
    if (visiblePos.isNull())
        visiblePos = firstPositionInOrBeforeNode(node);
    return visiblePos;
}

Document* Frame::documentAtPoint(const IntPoint& point)
{
    if (!view())
        return nullptr;

    IntPoint pt = view()->windowToContents(point);
    HitTestResult result = HitTestResult(pt);

    if (contentRenderer())
        result = eventHandler().hitTestResultAtPoint(pt, HitTestRequest::ReadOnly | HitTestRequest::Active | HitTestRequest::DisallowUserAgentShadowContent | HitTestRequest::AllowChildFrameContent);
    return result.innerNode() ? &result.innerNode()->document() : 0;
}

RefPtr<Range> Frame::rangeForPoint(const IntPoint& framePoint)
{
    VisiblePosition position = visiblePositionForPoint(framePoint);
    if (position.isNull())
        return nullptr;

    Position deepPosition = position.deepEquivalent();
    Text* containerText = deepPosition.containerText();
    if (!containerText || !containerText->renderer() || containerText->renderer()->style().userSelect() == UserSelect::None)
        return nullptr;

    VisiblePosition previous = position.previous();
    if (previous.isNotNull()) {
        RefPtr<Range> previousCharacterRange = makeRange(previous, position);
        LayoutRect rect = editor().firstRectForRange(previousCharacterRange.get());
        if (rect.contains(framePoint))
            return previousCharacterRange;
    }

    VisiblePosition next = position.next();
    if (RefPtr<Range> nextCharacterRange = makeRange(position, next)) {
        LayoutRect rect = editor().firstRectForRange(nextCharacterRange.get());
        if (rect.contains(framePoint))
            return nextCharacterRange;
    }

    return nullptr;
}

void Frame::createView(const IntSize& viewportSize, const Optional<Color>& backgroundColor,
    const IntSize& fixedLayoutSize, const IntRect& fixedVisibleContentRect,
    bool useFixedLayout, ScrollbarMode horizontalScrollbarMode, bool horizontalLock,
    ScrollbarMode verticalScrollbarMode, bool verticalLock)
{
    ASSERT(m_page);

    bool isMainFrame = this->isMainFrame();

    if (isMainFrame && view())
        view()->setParentVisible(false);

    setView(nullptr);

    RefPtr<FrameView> frameView;
    if (isMainFrame) {
        frameView = FrameView::create(*this, viewportSize);
        frameView->setFixedLayoutSize(fixedLayoutSize);
#if USE(COORDINATED_GRAPHICS)
        frameView->setFixedVisibleContentRect(fixedVisibleContentRect);
#else
        UNUSED_PARAM(fixedVisibleContentRect);
#endif
        frameView->setUseFixedLayout(useFixedLayout);
    } else
        frameView = FrameView::create(*this);

    frameView->setScrollbarModes(horizontalScrollbarMode, verticalScrollbarMode, horizontalLock, verticalLock);

    setView(frameView.copyRef());

    frameView->updateBackgroundRecursively(backgroundColor);

    if (isMainFrame)
        frameView->setParentVisible(true);

    if (ownerRenderer())
        ownerRenderer()->setWidget(frameView);

    if (HTMLFrameOwnerElement* owner = ownerElement())
        view()->setCanHaveScrollbars(owner->scrollingMode() != ScrollbarAlwaysOff);
}

DOMWindow* Frame::window() const
{
    return document() ? document()->domWindow() : nullptr;
}

AbstractDOMWindow* Frame::virtualWindow() const
{
    return window();
}

String Frame::layerTreeAsText(LayerTreeFlags flags) const
{
    document()->updateLayout();

    if (!contentRenderer())
        return String();

    return contentRenderer()->compositor().layerTreeAsText(flags);
}

String Frame::trackedRepaintRectsAsText() const
{
    if (!m_view)
        return String();
    return m_view->trackedRepaintRectsAsText();
}

void Frame::setPageZoomFactor(float factor)
{
    setPageAndTextZoomFactors(factor, m_textZoomFactor);
}

void Frame::setTextZoomFactor(float factor)
{
    setPageAndTextZoomFactors(m_pageZoomFactor, factor);
}

void Frame::setPageAndTextZoomFactors(float pageZoomFactor, float textZoomFactor)
{
    if (m_pageZoomFactor == pageZoomFactor && m_textZoomFactor == textZoomFactor)
        return;

    Page* page = this->page();
    if (!page)
        return;

    Document* document = this->document();
    if (!document)
        return;

    m_editor->dismissCorrectionPanelAsIgnored();

    // Respect SVGs zoomAndPan="disabled" property in standalone SVG documents.
    // FIXME: How to handle compound documents + zoomAndPan="disabled"? Needs SVG WG clarification.
    if (is<SVGDocument>(*document) && !downcast<SVGDocument>(*document).zoomAndPanEnabled())
        return;

    if (m_pageZoomFactor != pageZoomFactor) {
        if (FrameView* view = this->view()) {
            // Update the scroll position when doing a full page zoom, so the content stays in relatively the same position.
            LayoutPoint scrollPosition = view->scrollPosition();
            float percentDifference = (pageZoomFactor / m_pageZoomFactor);
            view->setScrollPosition(IntPoint(scrollPosition.x() * percentDifference, scrollPosition.y() * percentDifference));
        }
    }

    m_pageZoomFactor = pageZoomFactor;
    m_textZoomFactor = textZoomFactor;

    document->resolveStyle(Document::ResolveStyleType::Rebuild);

    for (RefPtr<Frame> child = tree().firstChild(); child; child = child->tree().nextSibling())
        child->setPageAndTextZoomFactors(m_pageZoomFactor, m_textZoomFactor);

    if (FrameView* view = this->view()) {
        if (document->renderView() && document->renderView()->needsLayout() && view->didFirstLayout())
            view->layoutContext().layout();
    }
}

float Frame::frameScaleFactor() const
{
    Page* page = this->page();

    // Main frame is scaled with respect to he container but inner frames are not scaled with respect to the main frame.
    if (!page || &page->mainFrame() != this || settings().delegatesPageScaling())
        return 1;

    return page->pageScaleFactor();
}

void Frame::suspendActiveDOMObjectsAndAnimations()
{
    bool wasSuspended = activeDOMObjectsAndAnimationsSuspended();

    m_activeDOMObjectsAndAnimationsSuspendedCount++;

    if (wasSuspended)
        return;

    // FIXME: Suspend/resume calls will not match if the frame is navigated, and gets a new document.
    clearTimers(); // Suspends animations and pending relayouts.
    if (m_doc)
        m_doc->suspendScheduledTasks(ReasonForSuspension::PageWillBeSuspended);
}

void Frame::resumeActiveDOMObjectsAndAnimations()
{
    if (!activeDOMObjectsAndAnimationsSuspended())
        return;

    m_activeDOMObjectsAndAnimationsSuspendedCount--;

    if (activeDOMObjectsAndAnimationsSuspended())
        return;

    if (!m_doc)
        return;

    // FIXME: Suspend/resume calls will not match if the frame is navigated, and gets a new document.
    m_doc->resumeScheduledTasks(ReasonForSuspension::PageWillBeSuspended);

    // Frame::clearTimers() suspended animations and pending relayouts.
    animation().resumeAnimationsForDocument(m_doc.get());
    if (m_view)
        m_view->layoutContext().scheduleLayout();
}

void Frame::deviceOrPageScaleFactorChanged()
{
    for (RefPtr<Frame> child = tree().firstChild(); child; child = child->tree().nextSibling())
        child->deviceOrPageScaleFactorChanged();

    if (RenderView* root = contentRenderer())
        root->compositor().deviceOrPageScaleFactorChanged();
}

bool Frame::isAlwaysOnLoggingAllowed() const
{
    return page() && page()->isAlwaysOnLoggingAllowed();
}

void Frame::dropChildren()
{
    ASSERT(isMainFrame());
    while (Frame* child = tree().firstChild())
        tree().removeChild(*child);
}

void Frame::didPrewarmLocalStorage()
{
    ASSERT(isMainFrame());
    ASSERT(m_localStoragePrewarmingCount < maxlocalStoragePrewarmingCount);
    ++m_localStoragePrewarmingCount;
}

bool Frame::mayPrewarmLocalStorage() const
{
    ASSERT(isMainFrame());
    return m_localStoragePrewarmingCount < maxlocalStoragePrewarmingCount;
}

void Frame::selfOnlyRef()
{
    ASSERT(isMainFrame());
    if (m_selfOnlyRefCount++)
        return;

    ref();
}

void Frame::selfOnlyDeref()
{
    ASSERT(isMainFrame());
    ASSERT(m_selfOnlyRefCount);
    if (--m_selfOnlyRefCount)
        return;

    if (hasOneRef())
        dropChildren();

    deref();
}

} // namespace WebCore