Avoid creating temporary blank WebContents

- Avoid creating a blank WebContents for new QWebEnginePages only to replace it
  with a different blank WebContents moments later. This problem is already
  solved in QQuickWebEngineView by lazy initialization, therefore the patch
  moves this lazy initialization into WebContentsAdapter itself so that it can
  be applied to both QQuickWebEngineView and QWebEnginePage.

- Try to delay WebContents creation until the first navigation so that we have
  enough information available to pick the right initial SiteInstance when
  calling WebContents::Create. This is done by triggering WebContents creation
  from the first call to a WebContentsAdapter::load* method.

- Use the SiteInstance from WebContentsDelegate::OpenURLFromTab. This method
  gets a SiteInstance pointer which we should give to WebContents::Create.

Task-number: QTBUG-65561
Task-number: QTBUG-67163
Change-Id: Id7b351998adefb810cf27c61a1447b61d7f4c606
Reviewed-by: Allan Sandfeld Jensen <allan.jensen@qt.io>

3 files changed, 92 insertions, 148 deletions

diff --git a/src/webengine/api/qquickwebenginehistory.cpp b/src/webengine/api/qquickwebenginehistory.cpp
index 970bfb22d..d3c4a0026 100644
--- a/src/webengine/api/qquickwebenginehistory.cpp
+++ b/src/webengine/api/qquickwebenginehistory.cpp
@@ -58,8 +58,6 @@ QQuickWebEngineHistoryListModelPrivate::~QQuickWebEngineHistoryListModelPrivate(
 
 int QQuickWebEngineHistoryListModelPrivate::count() const
 {
-    if (!adapter())
-        return 0;
     return adapter()->navigationEntryCount();
 }
 
@@ -70,8 +68,6 @@ int QQuickWebEngineHistoryListModelPrivate::index(int index) const
 
 int QQuickWebEngineHistoryListModelPrivate::offsetForIndex(int index) const
 {
-    if (!adapter())
-        return index;
     return index - adapter()->currentNavigationEntryIndex();
 }
 
@@ -87,8 +83,6 @@ QQuickWebEngineBackHistoryListModelPrivate::QQuickWebEngineBackHistoryListModelP
 
 int QQuickWebEngineBackHistoryListModelPrivate::count() const
 {
-    if (!adapter())
-        return 0;
     return adapter()->currentNavigationEntryIndex();
 }
 
@@ -110,15 +104,13 @@ QQuickWebEngineForwardHistoryListModelPrivate::QQuickWebEngineForwardHistoryList
 
 int QQuickWebEngineForwardHistoryListModelPrivate::count() const
 {
-    if (!adapter())
+    if (!adapter()->isInitialized())
         return 0;
     return adapter()->navigationEntryCount() - adapter()->currentNavigationEntryIndex() - 1;
 }
 
 int QQuickWebEngineForwardHistoryListModelPrivate::index(int i) const
 {
-    if (!adapter())
-        return i + 1;
     return adapter()->currentNavigationEntryIndex() + i + 1;
 }
 
diff --git a/src/webengine/api/qquickwebengineview.cpp b/src/webengine/api/qquickwebengineview.cpp
index 2fe146d4c..18c54c263 100644
--- a/src/webengine/api/qquickwebengineview.cpp
+++ b/src/webengine/api/qquickwebengineview.cpp
@@ -103,7 +103,7 @@ static QAccessibleInterface *webAccessibleFactory(const QString &, QObject *obje
 #endif // QT_NO_ACCESSIBILITY
 
 QQuickWebEngineViewPrivate::QQuickWebEngineViewPrivate()
-    : adapter(0)
+    : adapter(QSharedPointer<WebContentsAdapter>::create())
     , m_history(new QQuickWebEngineHistory(this))
     , m_profile(QQuickWebEngineProfile::defaultProfile())
     , m_settings(new QQuickWebEngineSettings(m_profile->settings()))
@@ -119,6 +119,7 @@ QQuickWebEngineViewPrivate::QQuickWebEngineViewPrivate()
     , devicePixelRatio(QGuiApplication::primaryScreen()->devicePixelRatio())
     , m_webChannel(0)
     , m_webChannelWorld(0)
+    , m_isBeingAdopted(false)
     , m_dpiScale(1.0)
     , m_backgroundColor(Qt::white)
     , m_defaultZoomFactor(1.0)
@@ -226,7 +227,7 @@ void QQuickWebEngineViewPrivate::navigationRequested(int navigationType, const Q
     Q_EMIT q->navigationRequested(&navigationRequest);
 
     navigationRequestAction = navigationRequest.action();
-    if ((navigationRequestAction == WebContentsAdapterClient::AcceptRequest) && adapter && adapter->isFindTextInProgress())
+    if ((navigationRequestAction == WebContentsAdapterClient::AcceptRequest) && adapter->isFindTextInProgress())
         adapter->stopFinding();
 }
 
@@ -705,47 +706,15 @@ void QQuickWebEngineViewPrivate::adoptWebContents(WebContentsAdapter *webContent
         return;
     }
 
-    Q_Q(QQuickWebEngineView);
+    m_isBeingAdopted = true;
 
     // This throws away the WebContentsAdapter that has been used until now.
     // All its states, particularly the loading URL, are replaced by the adopted WebContentsAdapter.
-    if (adapter) {
-        WebContentsAdapterOwner *adapterOwner = new WebContentsAdapterOwner(adapter->sharedFromThis());
-        adapterOwner->deleteLater();
-    }
-    adapter = webContents->sharedFromThis();
-    adapter->initialize(this);
-
-    // associate the webChannel with the new adapter
-    if (m_webChannel)
-        adapter->setWebChannel(m_webChannel, m_webChannelWorld);
-
-    if (devToolsView && devToolsView->d_ptr->adapter)
-        adapter->openDevToolsFrontend(devToolsView->d_ptr->adapter);
-    else if (inspectedView && inspectedView->d_ptr->adapter)
-        inspectedView->d_ptr->adapter->openDevToolsFrontend(adapter);
-
-    // set initial background color if non-default
-    if (m_backgroundColor != Qt::white)
-        adapter->backgroundColorChanged();
-
-    // re-bind the userscrips to the new adapter
-    Q_FOREACH (QQuickWebEngineScript *script, m_userScripts)
-        script->d_func()->bind(browserContextAdapter()->userResourceController(), adapter.data());
-
-    // set the zoomFactor if it had been changed on the old adapter.
-    if (!qFuzzyCompare(adapter->currentZoomFactor(), m_defaultZoomFactor))
-        q->setZoomFactor(m_defaultZoomFactor);
+    WebContentsAdapterOwner *adapterOwner = new WebContentsAdapterOwner(adapter->sharedFromThis());
+    adapterOwner->deleteLater();
 
-    // Emit signals for values that might be different from the previous WebContentsAdapter.
-    emit q->titleChanged();
-    emit q->urlChanged();
-    emit q->iconChanged();
-    // FIXME: The current loading state should be stored in the WebContentAdapter
-    // and it should be checked here if the signal emission is really necessary.
-    QQuickWebEngineLoadRequest loadRequest(adapter->activeUrl(), QQuickWebEngineView::LoadSucceededStatus);
-    emit q->loadingChanged(&loadRequest);
-    emit q->loadProgressChanged();
+    adapter = webContents->sharedFromThis();
+    adapter->setClient(this);
 }
 
 QQuickWebEngineView::QQuickWebEngineView(QQuickItem *parent)
@@ -754,6 +723,8 @@ QQuickWebEngineView::QQuickWebEngineView(QQuickItem *parent)
 {
     Q_D(QQuickWebEngineView);
     d->q_ptr = this;
+    d->adapter->setClient(d);
+
     this->setActiveFocusOnTab(true);
     this->setFlags(QQuickItem::ItemIsFocusScope | QQuickItem::ItemAcceptsDrops);
 }
@@ -761,36 +732,53 @@ QQuickWebEngineView::QQuickWebEngineView(QQuickItem *parent)
 QQuickWebEngineView::~QQuickWebEngineView()
 {
     Q_D(QQuickWebEngineView);
-    if (d->adapter)
-        d->adapter->stopFinding();
+    d->adapter->stopFinding();
     if (d->faviconProvider)
         d->faviconProvider->detach(this);
 }
 
 void QQuickWebEngineViewPrivate::ensureContentsAdapter()
 {
-    Q_Q(QQuickWebEngineView);
-    if (!adapter) {
-        adapter = QSharedPointer<WebContentsAdapter>::create();
-        adapter->initialize(this);
-        if (m_backgroundColor != Qt::white)
-            adapter->backgroundColorChanged();
-        if (m_webChannel)
-            adapter->setWebChannel(m_webChannel, m_webChannelWorld);
+    if (!adapter->isInitialized()) {
         if (explicitUrl.isValid())
             adapter->load(explicitUrl);
-        if (inspectedView)
-            inspectedView->d_ptr->adapter->openDevToolsFrontend(adapter);
-        // push down the page's user scripts
-        Q_FOREACH (QQuickWebEngineScript *script, m_userScripts)
-            script->d_func()->bind(browserContextAdapter()->userResourceController(), adapter.data());
-        // set the zoomFactor if it had been changed on the old adapter.
-        if (!qFuzzyCompare(adapter->currentZoomFactor(), m_defaultZoomFactor))
-            q->setZoomFactor(m_defaultZoomFactor);
-
+        else
+            adapter->loadDefault();
     }
 }
 
+void QQuickWebEngineViewPrivate::initializationFinished()
+{
+    Q_Q(QQuickWebEngineView);
+
+    if (m_backgroundColor != Qt::white)
+        adapter->backgroundColorChanged();
+    if (m_webChannel)
+        adapter->setWebChannel(m_webChannel, m_webChannelWorld);
+    if (!qFuzzyCompare(adapter->currentZoomFactor(), m_defaultZoomFactor))
+        q->setZoomFactor(m_defaultZoomFactor);
+    if (devToolsView && devToolsView->d_ptr->adapter)
+        adapter->openDevToolsFrontend(devToolsView->d_ptr->adapter);
+    else if (inspectedView && inspectedView->d_ptr->adapter)
+        inspectedView->d_ptr->adapter->openDevToolsFrontend(adapter);
+
+    Q_FOREACH (QQuickWebEngineScript *script, m_userScripts)
+        script->d_func()->bind(browserContextAdapter()->userResourceController(), adapter.data());
+
+    if (!m_isBeingAdopted)
+        return;
+
+    // Ideally these would only be emitted if something actually changed.
+    emit q->titleChanged();
+    emit q->urlChanged();
+    emit q->iconChanged();
+    QQuickWebEngineLoadRequest loadRequest(adapter->activeUrl(), QQuickWebEngineView::LoadSucceededStatus);
+    emit q->loadingChanged(&loadRequest);
+    emit q->loadProgressChanged();
+
+    m_isBeingAdopted = false;
+}
+
 void QQuickWebEngineViewPrivate::setFullScreenMode(bool fullscreen)
 {
     Q_Q(QQuickWebEngineView);
@@ -804,7 +792,7 @@ void QQuickWebEngineViewPrivate::setFullScreenMode(bool fullscreen)
 QUrl QQuickWebEngineView::url() const
 {
     Q_D(const QQuickWebEngineView);
-    return d->explicitUrl.isValid() ? d->explicitUrl : (d->adapter ? d->adapter->activeUrl() : QUrl());
+    return d->explicitUrl.isValid() ? d->explicitUrl : d->adapter->activeUrl();
 }
 
 void QQuickWebEngineView::setUrl(const QUrl& url)
@@ -814,7 +802,7 @@ void QQuickWebEngineView::setUrl(const QUrl& url)
 
     Q_D(QQuickWebEngineView);
     d->explicitUrl = url;
-    if (d->adapter)
+    if (d->adapter->isInitialized())
         d->adapter->load(url);
     if (!qmlEngine(this) || isComponentComplete())
         d->ensureContentsAdapter();
@@ -832,47 +820,37 @@ void QQuickWebEngineView::loadHtml(const QString &html, const QUrl &baseUrl)
     d->explicitUrl = QUrl();
     if (!qmlEngine(this) || isComponentComplete())
         d->ensureContentsAdapter();
-    if (d->adapter)
+    if (d->adapter->isInitialized())
         d->adapter->setContent(html.toUtf8(), QStringLiteral("text/html;charset=UTF-8"), baseUrl);
 }
 
 void QQuickWebEngineView::goBack()
 {
     Q_D(QQuickWebEngineView);
-    if (!d->adapter)
-        return;
     d->adapter->navigateToOffset(-1);
 }
 
 void QQuickWebEngineView::goForward()
 {
     Q_D(QQuickWebEngineView);
-    if (!d->adapter)
-        return;
     d->adapter->navigateToOffset(1);
 }
 
 void QQuickWebEngineView::reload()
 {
     Q_D(QQuickWebEngineView);
-    if (!d->adapter)
-        return;
     d->adapter->reload();
 }
 
 void QQuickWebEngineView::reloadAndBypassCache()
 {
     Q_D(QQuickWebEngineView);
-    if (!d->adapter)
-        return;
     d->adapter->reloadAndBypassCache();
 }
 
 void QQuickWebEngineView::stop()
 {
     Q_D(QQuickWebEngineView);
-    if (!d->adapter)
-        return;
     d->adapter->stop();
 }
 
@@ -881,9 +859,6 @@ void QQuickWebEngineView::setZoomFactor(qreal arg)
     Q_D(QQuickWebEngineView);
     d->m_defaultZoomFactor = arg;
 
-    if (!d->adapter)
-        return;
-
     qreal oldFactor = d->adapter->currentZoomFactor();
     d->adapter->setZoomFactor(arg);
     if (qFuzzyCompare(oldFactor, d->adapter->currentZoomFactor()))
@@ -930,14 +905,20 @@ void QQuickWebEngineViewPrivate::setProfile(QQuickWebEngineProfile *profile)
     Q_EMIT q->profileChanged();
     m_settings->setParentSettings(profile->settings());
 
-    if (adapter && adapter->browserContext() != browserContextAdapter()->browserContext()) {
+    if (adapter->browserContext() != browserContextAdapter()->browserContext()) {
         // When the profile changes we need to create a new WebContentAdapter and reload the active URL.
+        bool wasInitialized = adapter->isInitialized();
         QUrl activeUrl = adapter->activeUrl();
-        adapter.reset();
-        ensureContentsAdapter();
-
-        if (!explicitUrl.isValid() && activeUrl.isValid())
-            adapter->load(activeUrl);
+        adapter = QSharedPointer<WebContentsAdapter>::create();
+        adapter->setClient(this);
+        if (wasInitialized) {
+            if (explicitUrl.isValid())
+                adapter->load(explicitUrl);
+            else if (activeUrl.isValid())
+                adapter->load(activeUrl);
+            else
+                adapter->loadDefault();
+        }
     }
 }
 
@@ -1053,43 +1034,30 @@ int QQuickWebEngineView::loadProgress() const
 QString QQuickWebEngineView::title() const
 {
     Q_D(const QQuickWebEngineView);
-    if (!d->adapter)
-        return QString();
     return d->adapter->pageTitle();
 }
 
 bool QQuickWebEngineView::canGoBack() const
 {
     Q_D(const QQuickWebEngineView);
-    if (!d->adapter)
-        return false;
     return d->adapter->canGoBack();
 }
 
 bool QQuickWebEngineView::canGoForward() const
 {
     Q_D(const QQuickWebEngineView);
-    if (!d->adapter)
-        return false;
     return d->adapter->canGoForward();
 }
 
 void QQuickWebEngineView::runJavaScript(const QString &script, const QJSValue &callback)
 {
-    Q_D(QQuickWebEngineView);
-    d->ensureContentsAdapter();
-    if (!callback.isUndefined()) {
-        quint64 requestId = d_ptr->adapter->runJavaScriptCallbackResult(script, QQuickWebEngineScript::MainWorld);
-        d->m_callbacks.insert(requestId, callback);
-    } else
-        d->adapter->runJavaScript(script, QQuickWebEngineScript::MainWorld);
+    runJavaScript(script, QQuickWebEngineScript::MainWorld, callback);
 }
 
 void QQuickWebEngineView::runJavaScript(const QString &script, quint32 worldId, const QJSValue &callback)
 {
     Q_D(QQuickWebEngineView);
-    if (!d->adapter)
-        return;
+    d->ensureContentsAdapter();
     if (!callback.isUndefined()) {
         quint64 requestId = d_ptr->adapter->runJavaScriptCallbackResult(script, worldId);
         d->m_callbacks.insert(requestId, callback);
@@ -1100,7 +1068,7 @@ void QQuickWebEngineView::runJavaScript(const QString &script, quint32 worldId,
 qreal QQuickWebEngineView::zoomFactor() const
 {
     Q_D(const QQuickWebEngineView);
-    if (!d->adapter)
+    if (!d->adapter->isInitialized())
         return d->m_defaultZoomFactor;
     return d->adapter->currentZoomFactor();
 }
@@ -1117,8 +1085,7 @@ void QQuickWebEngineView::setBackgroundColor(const QColor &color)
     if (color == d->m_backgroundColor)
         return;
     d->m_backgroundColor = color;
-    if (d->adapter)
-        d->adapter->backgroundColorChanged();
+    d->adapter->backgroundColorChanged();
     emit backgroundColorChanged();
 }
 
@@ -1132,39 +1099,32 @@ void QQuickWebEngineView::setBackgroundColor(const QColor &color)
 bool QQuickWebEngineView::isAudioMuted() const
 {
     const Q_D(QQuickWebEngineView);
-    if (d->adapter)
-        return d->adapter->isAudioMuted();
-    return false;
+    return d->adapter->isAudioMuted();
 }
 
 void QQuickWebEngineView::setAudioMuted(bool muted)
 {
     Q_D(QQuickWebEngineView);
-    bool _isAudioMuted = isAudioMuted();
-    if (d->adapter) {
-        d->adapter->setAudioMuted(muted);
-        if (_isAudioMuted != muted) {
-            Q_EMIT audioMutedChanged(muted);
-        }
-    }
+    bool wasAudioMuted = d->adapter->isAudioMuted();
+    d->adapter->setAudioMuted(muted);
+    if (wasAudioMuted != d->adapter->isAudioMuted())
+        Q_EMIT audioMutedChanged(muted);
 }
 
 bool QQuickWebEngineView::recentlyAudible() const
 {
     const Q_D(QQuickWebEngineView);
-    if (d->adapter)
-        return d->adapter->recentlyAudible();
-    return false;
+    return d->adapter->recentlyAudible();
 }
 
 void QQuickWebEngineView::printToPdf(const QString& filePath, PrintedPageSizeId pageSizeId, PrintedPageOrientation orientation)
 {
 #if defined(ENABLE_PDF)
-    Q_D(const QQuickWebEngineView);
+    Q_D(QQuickWebEngineView);
     QPageSize layoutSize(static_cast<QPageSize::PageSizeId>(pageSizeId));
     QPageLayout::Orientation layoutOrientation = static_cast<QPageLayout::Orientation>(orientation);
     QPageLayout pageLayout(layoutSize, layoutOrientation, QMarginsF(0.0, 0.0, 0.0, 0.0));
-
+    d->ensureContentsAdapter();
     d->adapter->printToPDF(pageLayout, filePath);
 #else
     Q_UNUSED(filePath);
@@ -1184,6 +1144,7 @@ void QQuickWebEngineView::printToPdf(const QJSValue &callback, PrintedPageSizeId
     if (callback.isUndefined())
         return;
 
+    d->ensureContentsAdapter();
     quint64 requestId = d->adapter->printToPDFCallbackResult(pageLayout);
     d->m_callbacks.insert(requestId, callback);
 #else
@@ -1213,7 +1174,7 @@ bool QQuickWebEngineView::isFullScreen() const
 void QQuickWebEngineView::findText(const QString &subString, FindFlags options, const QJSValue &callback)
 {
     Q_D(QQuickWebEngineView);
-    if (!d->adapter)
+    if (!d->adapter->isInitialized())
         return;
     if (subString.isEmpty()) {
         d->adapter->stopFinding();
@@ -1240,8 +1201,7 @@ QQmlWebChannel *QQuickWebEngineView::webChannel()
     Q_D(QQuickWebEngineView);
     if (!d->m_webChannel) {
         d->m_webChannel = new QQmlWebChannel(this);
-        if (d->adapter)
-            d->adapter->setWebChannel(d->m_webChannel, d->m_webChannelWorld);
+        d->adapter->setWebChannel(d->m_webChannel, d->m_webChannelWorld);
     }
 
     return d->m_webChannel;
@@ -1253,8 +1213,7 @@ void QQuickWebEngineView::setWebChannel(QQmlWebChannel *webChannel)
     if (d->m_webChannel == webChannel)
         return;
     d->m_webChannel = webChannel;
-    if (d->adapter)
-        d->adapter->setWebChannel(webChannel, d->m_webChannelWorld);
+    d->adapter->setWebChannel(webChannel, d->m_webChannelWorld);
     Q_EMIT webChannelChanged();
 }
 
@@ -1270,8 +1229,7 @@ void QQuickWebEngineView::setWebChannelWorld(uint webChannelWorld)
     if (d->m_webChannelWorld == webChannelWorld)
         return;
     d->m_webChannelWorld = webChannelWorld;
-    if (d->adapter)
-        d->adapter->setWebChannel(d->m_webChannel, d->m_webChannelWorld);
+    d->adapter->setWebChannel(d->m_webChannel, d->m_webChannelWorld);
     Q_EMIT webChannelWorldChanged(webChannelWorld);
 }
 
@@ -1314,19 +1272,15 @@ void QQuickWebEngineView::setDevToolsView(QQuickWebEngineView *devToolsView)
     d->devToolsView = devToolsView;
     if (devToolsView)
         devToolsView->setInspectedView(this);
-    if (d->adapter) {
-        if (devToolsView)
-            d->adapter->openDevToolsFrontend(devToolsView->d_ptr->adapter);
-        else
-            d->adapter->closeDevToolsFrontend();
-    }
+    if (devToolsView)
+        d->adapter->openDevToolsFrontend(devToolsView->d_ptr->adapter);
+    else
+        d->adapter->closeDevToolsFrontend();
     Q_EMIT devToolsViewChanged();
 }
 
 void QQuickWebEngineView::grantFeaturePermission(const QUrl &securityOrigin, QQuickWebEngineView::Feature feature, bool granted)
 {
-    if (!d_ptr->adapter)
-        return;
     if (!granted && ((feature >= MediaAudioCapture && feature <= MediaAudioVideoCapture) ||
                      (feature >= DesktopVideoCapture && feature <= DesktopAudioVideoCapture))) {
          d_ptr->adapter->grantMediaAccessPermission(securityOrigin, WebContentsAdapterClient::MediaNone);
@@ -1374,8 +1328,6 @@ void QQuickWebEngineView::setActiveFocusOnPress(bool arg)
 void QQuickWebEngineView::goBackOrForward(int offset)
 {
     Q_D(QQuickWebEngineView);
-    if (!d->adapter)
-        return;
     const int current = d->adapter->currentNavigationEntryIndex();
     const int count = d->adapter->navigationEntryCount();
     const int index = current + offset;
@@ -1404,7 +1356,7 @@ void QQuickWebEngineView::geometryChanged(const QRectF &newGeometry, const QRect
 void QQuickWebEngineView::itemChange(ItemChange change, const ItemChangeData &value)
 {
     Q_D(QQuickWebEngineView);
-    if (d->adapter && (change == ItemSceneChange || change == ItemVisibleHasChanged)) {
+    if (d->adapter->isInitialized() && (change == ItemSceneChange || change == ItemVisibleHasChanged)) {
         if (window() && isVisible())
             d->adapter->wasShown();
         else
@@ -1666,16 +1618,12 @@ void QQuickWebEngineView::triggerWebAction(WebAction action)
 QSizeF QQuickWebEngineView::contentsSize() const
 {
     Q_D(const QQuickWebEngineView);
-    if (!d->adapter)
-        return QSizeF();
     return d->adapter->lastContentsSize();
 }
 
 QPointF QQuickWebEngineView::scrollPosition() const
 {
     Q_D(const QQuickWebEngineView);
-    if (!d->adapter)
-        return QPointF();
     return d->adapter->lastScrollOffset();
 }
 
@@ -1683,11 +1631,11 @@ void QQuickWebEngineViewPrivate::userScripts_append(QQmlListProperty<QQuickWebEn
 {
     Q_ASSERT(p && p->data);
     QQuickWebEngineViewPrivate *d = static_cast<QQuickWebEngineViewPrivate*>(p->data);
-    UserResourceControllerHost *resourceController = d->browserContextAdapter()->userResourceController();
     d->m_userScripts.append(script);
-    // If the adapter hasn't been instantiated, we'll bind the scripts in ensureContentsAdapter()
-    if (!d->adapter)
+    // If the adapter hasn't been initialized, we'll bind the scripts in initializationFinished()
+    if (!d->adapter->isInitialized())
         return;
+    UserResourceControllerHost *resourceController = d->browserContextAdapter()->userResourceController();
     script->d_func()->bind(resourceController, d->adapter.data());
 }
 
@@ -1709,9 +1657,11 @@ void QQuickWebEngineViewPrivate::userScripts_clear(QQmlListProperty<QQuickWebEng
 {
     Q_ASSERT(p && p->data);
     QQuickWebEngineViewPrivate *d = static_cast<QQuickWebEngineViewPrivate*>(p->data);
+    d->m_userScripts.clear();
+    if (!d->adapter->isInitialized())
+        return;
     UserResourceControllerHost *resourceController = d->browserContextAdapter()->userResourceController();
     resourceController->clearAllScripts(d->adapter.data());
-    d->m_userScripts.clear();
 }
 
 void QQuickWebEngineView::componentComplete()
diff --git a/src/webengine/api/qquickwebengineview_p_p.h b/src/webengine/api/qquickwebengineview_p_p.h
index 4b8617749..7369a63be 100644
--- a/src/webengine/api/qquickwebengineview_p_p.h
+++ b/src/webengine/api/qquickwebengineview_p_p.h
@@ -93,6 +93,7 @@ public:
 
     QtWebEngineCore::RenderWidgetHostViewQtDelegate* CreateRenderWidgetHostViewQtDelegate(QtWebEngineCore::RenderWidgetHostViewQtDelegateClient *client) override;
     QtWebEngineCore::RenderWidgetHostViewQtDelegate* CreateRenderWidgetHostViewQtDelegateForPopup(QtWebEngineCore::RenderWidgetHostViewQtDelegateClient *client) override;
+    void initializationFinished() override;
     void titleChanged(const QString&) override;
     void urlChanged(const QUrl&) override;
     void iconChanged(const QUrl&) override;
@@ -185,6 +186,7 @@ public:
     QPointer<QQuickWebEngineView> inspectedView;
     QPointer<QQuickWebEngineView> devToolsView;
     uint m_webChannelWorld;
+    bool m_isBeingAdopted;
 
 private:
     QScopedPointer<QtWebEngineCore::UIDelegatesManager> m_uIDelegatesManager;