Add a backgroundColor property

This also allows setting a transparent color to see through
the web view's body if its background color isn't specified.

The color is initially held by the top API view and is pulled
by the WebContentsAdapter in order to set it on the RenderView.
Since both blink and our local compositors (in the QOpenGLWidget
case) need to know about this color, RWHVQt takes care of pushing
it to both. The former through an IPC message and the latter
directly on the RWHVQtDelegate.

Task-number: QTBUG-41960
Change-Id: Ie13317b2d087f5612ad9c5fb0e05ca3e91aec9af
Reviewed-by: Allan Sandfeld Jensen <allan.jensen@theqtcompany.com>
Reviewed-by: Andras Becsi <andras.becsi@theqtcompany.com>

22 files changed, 141 insertions, 2 deletions

diff --git a/src/core/common/qt_messages.h b/src/core/common/qt_messages.h
index c692ee5ca..25a995b27 100644
--- a/src/core/common/qt_messages.h
+++ b/src/core/common/qt_messages.h
@@ -31,6 +31,9 @@ IPC_MESSAGE_ROUTED1(QtRenderViewObserver_FetchDocumentMarkup,
 IPC_MESSAGE_ROUTED1(QtRenderViewObserver_FetchDocumentInnerText,
                     uint64 /* requestId */)
 
+IPC_MESSAGE_ROUTED1(QtRenderViewObserver_SetBackgroundColor,
+                    uint32 /* color */)
+
 IPC_MESSAGE_ROUTED1(WebChannelIPCTransport_Message, std::vector<char> /*binaryJSON*/)
 
 // User scripts messages
diff --git a/src/core/render_widget_host_view_qt.cpp b/src/core/render_widget_host_view_qt.cpp
index 46f93b90b..ef6610ecb 100644
--- a/src/core/render_widget_host_view_qt.cpp
+++ b/src/core/render_widget_host_view_qt.cpp
@@ -36,6 +36,7 @@
 
 #include "render_widget_host_view_qt.h"
 
+#include "common/qt_messages.h"
 #include "browser_accessibility_manager_qt.h"
 #include "browser_accessibility_qt.h"
 #include "chromium_overrides.h"
@@ -413,6 +414,14 @@ gfx::Rect RenderWidgetHostViewQt::GetViewBounds() const
     return gfx::BoundingRect(p1, p2);
 }
 
+void RenderWidgetHostViewQt::SetBackgroundColor(SkColor color) {
+    RenderWidgetHostViewBase::SetBackgroundColor(color);
+    // Set the background of the compositor if necessary
+    m_delegate->setClearColor(toQt(color));
+    // Set the background of the blink::FrameView
+    m_host->Send(new QtRenderViewObserver_SetBackgroundColor(m_host->GetRoutingID(), color));
+}
+
 // Return value indicates whether the mouse is locked successfully or not.
 bool RenderWidgetHostViewQt::LockMouse()
 {
diff --git a/src/core/render_widget_host_view_qt.h b/src/core/render_widget_host_view_qt.h
index 310ada429..274138dcf 100644
--- a/src/core/render_widget_host_view_qt.h
+++ b/src/core/render_widget_host_view_qt.h
@@ -126,6 +126,7 @@ public:
     virtual void Hide() Q_DECL_OVERRIDE;
     virtual bool IsShowing() Q_DECL_OVERRIDE;
     virtual gfx::Rect GetViewBounds() const Q_DECL_OVERRIDE;
+    virtual void SetBackgroundColor(SkColor color) Q_DECL_OVERRIDE;
     virtual bool LockMouse() Q_DECL_OVERRIDE;
     virtual void UnlockMouse() Q_DECL_OVERRIDE;
     virtual void MovePluginWindows(const std::vector<content::WebPluginGeometry>&) Q_DECL_OVERRIDE;
diff --git a/src/core/render_widget_host_view_qt_delegate.h b/src/core/render_widget_host_view_qt_delegate.h
index da595b91f..f4aa9b27d 100644
--- a/src/core/render_widget_host_view_qt_delegate.h
+++ b/src/core/render_widget_host_view_qt_delegate.h
@@ -96,6 +96,7 @@ public:
     virtual void move(const QPoint &) = 0;
     virtual void inputMethodStateChanged(bool editorVisible) = 0;
     virtual void setTooltip(const QString &) = 0;
+    virtual void setClearColor(const QColor &color) = 0;
 };
 
 } // namespace QtWebEngineCore
diff --git a/src/core/renderer/qt_render_view_observer.cpp b/src/core/renderer/qt_render_view_observer.cpp
index 83534dadd..ba91e54ae 100644
--- a/src/core/renderer/qt_render_view_observer.cpp
+++ b/src/core/renderer/qt_render_view_observer.cpp
@@ -65,6 +65,11 @@ void QtRenderViewObserver::onFetchDocumentInnerText(quint64 requestId)
         render_view()->GetWebView()->mainFrame()->contentAsText(std::numeric_limits<std::size_t>::max())));
 }
 
+void QtRenderViewObserver::onSetBackgroundColor(quint32 color)
+{
+    render_view()->GetWebView()->setBaseBackgroundColor(color);
+}
+
 void QtRenderViewObserver::OnFirstVisuallyNonEmptyLayout()
 {
     Send(new QtRenderViewObserverHost_DidFirstVisuallyNonEmptyLayout(routing_id()));
@@ -76,6 +81,7 @@ bool QtRenderViewObserver::OnMessageReceived(const IPC::Message& message)
     IPC_BEGIN_MESSAGE_MAP(QtRenderViewObserver, message)
         IPC_MESSAGE_HANDLER(QtRenderViewObserver_FetchDocumentMarkup, onFetchDocumentMarkup)
         IPC_MESSAGE_HANDLER(QtRenderViewObserver_FetchDocumentInnerText, onFetchDocumentInnerText)
+        IPC_MESSAGE_HANDLER(QtRenderViewObserver_SetBackgroundColor, onSetBackgroundColor)
         IPC_MESSAGE_UNHANDLED(handled = false)
     IPC_END_MESSAGE_MAP()
     return handled;
diff --git a/src/core/renderer/qt_render_view_observer.h b/src/core/renderer/qt_render_view_observer.h
index cb77cd0c9..3f7829a92 100644
--- a/src/core/renderer/qt_render_view_observer.h
+++ b/src/core/renderer/qt_render_view_observer.h
@@ -47,6 +47,7 @@ public:
 private:
     void onFetchDocumentMarkup(quint64 requestId);
     void onFetchDocumentInnerText(quint64 requestId);
+    void onSetBackgroundColor(quint32 color);
 
     void OnFirstVisuallyNonEmptyLayout() Q_DECL_OVERRIDE;
 
diff --git a/src/core/type_conversion.h b/src/core/type_conversion.h
index 90bd38b81..d49edd203 100644
--- a/src/core/type_conversion.h
+++ b/src/core/type_conversion.h
@@ -129,6 +129,11 @@ inline QColor toQt(const SkColor &c)
     return QColor(SkColorGetR(c), SkColorGetG(c), SkColorGetB(c), SkColorGetA(c));
 }
 
+inline SkColor toSk(const QColor &c)
+{
+    return c.rgba();
+}
+
 inline QMatrix4x4 toQt(const SkMatrix44 &m)
 {
     QMatrix4x4 qtMatrix(
diff --git a/src/core/web_contents_adapter.cpp b/src/core/web_contents_adapter.cpp
index 4a4e7198e..210704148 100644
--- a/src/core/web_contents_adapter.cpp
+++ b/src/core/web_contents_adapter.cpp
@@ -837,6 +837,13 @@ void WebContentsAdapter::dpiScaleChanged()
         impl->NotifyScreenInfoChanged();
 }
 
+void WebContentsAdapter::backgroundColorChanged()
+{
+    Q_D(WebContentsAdapter);
+    if (content::RenderWidgetHostView *rwhv = d->webContents->GetRenderWidgetHostView())
+        rwhv->SetBackgroundColor(toSk(d->adapterClient->backgroundColor()));
+}
+
 content::WebContents *WebContentsAdapter::webContents() const
 {
     Q_D(const WebContentsAdapter);
diff --git a/src/core/web_contents_adapter.h b/src/core/web_contents_adapter.h
index db8449478..902cc61ff 100644
--- a/src/core/web_contents_adapter.h
+++ b/src/core/web_contents_adapter.h
@@ -132,6 +132,7 @@ public:
     void grantMouseLockPermission(bool granted);
 
     void dpiScaleChanged();
+    void backgroundColorChanged();
     QAccessibleInterface *browserAccessible();
     BrowserContextQt* browserContext();
     BrowserContextAdapter* browserContextAdapter();
diff --git a/src/core/web_contents_adapter_client.h b/src/core/web_contents_adapter_client.h
index 9bc7698a5..20a5ad7af 100644
--- a/src/core/web_contents_adapter_client.h
+++ b/src/core/web_contents_adapter_client.h
@@ -190,6 +190,7 @@ public:
     virtual void selectionChanged() = 0;
     virtual QRectF viewportRect() const = 0;
     virtual qreal dpiScale() const = 0;
+    virtual QColor backgroundColor() const = 0;
     virtual void loadStarted(const QUrl &provisionalUrl, bool isErrorPage = false) = 0;
     virtual void loadCommitted() = 0;
     virtual void loadVisuallyCommitted() = 0;
diff --git a/src/core/web_contents_view_qt.cpp b/src/core/web_contents_view_qt.cpp
index 004800d5a..aad44c1d9 100644
--- a/src/core/web_contents_view_qt.cpp
+++ b/src/core/web_contents_view_qt.cpp
@@ -82,6 +82,13 @@ content::RenderWidgetHostViewBase* WebContentsViewQt::CreateViewForPopupWidget(c
     return view;
 }
 
+void WebContentsViewQt::RenderViewCreated(content::RenderViewHost* host)
+{
+    // The render process is done creating the RenderView and it's ready to be routed
+    // messages at this point.
+    host->GetView()->SetBackgroundColor(toSk(m_client->backgroundColor()));
+}
+
 void WebContentsViewQt::CreateView(const gfx::Size& initial_size, gfx::NativeView context)
 {
     // This is passed through content::WebContents::CreateParams::context either as the native view's client
diff --git a/src/core/web_contents_view_qt.h b/src/core/web_contents_view_qt.h
index a19432fbe..cbbca2371 100644
--- a/src/core/web_contents_view_qt.h
+++ b/src/core/web_contents_view_qt.h
@@ -76,7 +76,7 @@ public:
 
     virtual void SetPageTitle(const base::string16& title) Q_DECL_OVERRIDE { }
 
-    virtual void RenderViewCreated(content::RenderViewHost* host) Q_DECL_OVERRIDE { QT_NOT_YET_IMPLEMENTED }
+    virtual void RenderViewCreated(content::RenderViewHost* host) Q_DECL_OVERRIDE;
 
     virtual void RenderViewSwappedIn(content::RenderViewHost* host) Q_DECL_OVERRIDE { QT_NOT_YET_IMPLEMENTED }
 
diff --git a/src/webengine/api/qquickwebengineview.cpp b/src/webengine/api/qquickwebengineview.cpp
index eea584d4d..1f5e56bdb 100644
--- a/src/webengine/api/qquickwebengineview.cpp
+++ b/src/webengine/api/qquickwebengineview.cpp
@@ -108,6 +108,7 @@ QQuickWebEngineViewPrivate::QQuickWebEngineViewPrivate()
     , m_activeFocusOnPress(true)
     , devicePixelRatio(QGuiApplication::primaryScreen()->devicePixelRatio())
     , m_dpiScale(1.0)
+    , m_backgroundColor(Qt::white)
 {
     // The gold standard for mobile web content is 160 dpi, and the devicePixelRatio expected
     // is the (possibly quantized) ratio of device dpi to 160 dpi.
@@ -365,6 +366,11 @@ qreal QQuickWebEngineViewPrivate::dpiScale() const
     return m_dpiScale;
 }
 
+QColor QQuickWebEngineViewPrivate::backgroundColor() const
+{
+    return m_backgroundColor;
+}
+
 void QQuickWebEngineViewPrivate::loadStarted(const QUrl &provisionalUrl, bool isErrorPage)
 {
     Q_Q(QQuickWebEngineView);
@@ -928,6 +934,34 @@ qreal QQuickWebEngineView::zoomFactor() const
     return d->adapter->currentZoomFactor();
 }
 
+/*!
+    \qmlproperty bool WebEngineView::backgroundColor
+    \since QtWebEngine 1.3
+
+    Sets this property to change the color of the WebEngineView's background,
+    behing the document's body. You can set it to "transparent" or to a translucent
+    color to see through the document, or you can set this color to match your
+    web content in an hybrid app to prevent the white flashes that may appear
+    during loading.
+
+    The default value is white.
+*/
+QColor QQuickWebEngineView::backgroundColor() const
+{
+    Q_D(const QQuickWebEngineView);
+    return d->m_backgroundColor;
+}
+
+void QQuickWebEngineView::setBackgroundColor(const QColor &color)
+{
+    Q_D(QQuickWebEngineView);
+    if (color == d->m_backgroundColor)
+        return;
+    d->m_backgroundColor = color;
+    d->ensureContentsAdapter();
+    d->adapter->backgroundColorChanged();
+    emit backgroundColorChanged();
+}
 
 bool QQuickWebEngineView::isFullScreen() const
 {
diff --git a/src/webengine/api/qquickwebengineview_p.h b/src/webengine/api/qquickwebengineview_p.h
index 5db15e873..e26e4f360 100644
--- a/src/webengine/api/qquickwebengineview_p.h
+++ b/src/webengine/api/qquickwebengineview_p.h
@@ -92,6 +92,7 @@ class Q_WEBENGINE_PRIVATE_EXPORT QQuickWebEngineView : public QQuickItem {
     Q_PROPERTY(QQmlWebChannel *webChannel READ webChannel WRITE setWebChannel NOTIFY webChannelChanged REVISION 1)
     Q_PROPERTY(QQmlListProperty<QQuickWebEngineScript> userScripts READ userScripts FINAL)
     Q_PROPERTY(bool activeFocusOnPress READ activeFocusOnPress WRITE setActiveFocusOnPress NOTIFY activeFocusOnPressChanged REVISION 2)
+    Q_PROPERTY(QColor backgroundColor READ backgroundColor WRITE setBackgroundColor NOTIFY backgroundColorChanged REVISION 3)
 
 #ifdef ENABLE_QML_TESTSUPPORT_API
     Q_PROPERTY(QQuickWebEngineTestSupport *testSupport READ testSupport WRITE setTestSupport FINAL)
@@ -122,6 +123,8 @@ public:
     bool isFullScreen() const;
     qreal zoomFactor() const;
     void setZoomFactor(qreal arg);
+    QColor backgroundColor() const;
+    void setBackgroundColor(const QColor &color);
 
     QQuickWebEngineViewExperimental *experimental() const;
 
@@ -274,6 +277,7 @@ Q_SIGNALS:
     Q_REVISION(1) void profileChanged();
     Q_REVISION(1) void webChannelChanged();
     Q_REVISION(2) void activeFocusOnPressChanged(bool);
+    Q_REVISION(3) void backgroundColorChanged();
 
 protected:
     void geometryChanged(const QRectF &newGeometry, const QRectF &oldGeometry);
diff --git a/src/webengine/api/qquickwebengineview_p_p.h b/src/webengine/api/qquickwebengineview_p_p.h
index 7e411d349..4d95de84e 100644
--- a/src/webengine/api/qquickwebengineview_p_p.h
+++ b/src/webengine/api/qquickwebengineview_p_p.h
@@ -123,6 +123,7 @@ public:
     virtual void selectionChanged() Q_DECL_OVERRIDE { }
     virtual QRectF viewportRect() const Q_DECL_OVERRIDE;
     virtual qreal dpiScale() const Q_DECL_OVERRIDE;
+    virtual QColor backgroundColor() const Q_DECL_OVERRIDE;
     virtual void loadStarted(const QUrl &provisionalUrl, bool isErrorPage = false) Q_DECL_OVERRIDE;
     virtual void loadCommitted() Q_DECL_OVERRIDE;
     virtual void loadVisuallyCommitted() Q_DECL_OVERRIDE;
@@ -194,6 +195,7 @@ private:
     QScopedPointer<QtWebEngineCore::UIDelegatesManager> m_uIDelegatesManager;
     QList<QQuickWebEngineScript *> m_userScripts;
     qreal m_dpiScale;
+    QColor m_backgroundColor;
 };
 
 #ifndef QT_NO_ACCESSIBILITY
diff --git a/src/webengine/render_widget_host_view_qt_delegate_quick.h b/src/webengine/render_widget_host_view_qt_delegate_quick.h
index ddd0e4d9e..eb2860b27 100644
--- a/src/webengine/render_widget_host_view_qt_delegate_quick.h
+++ b/src/webengine/render_widget_host_view_qt_delegate_quick.h
@@ -70,6 +70,8 @@ public:
     virtual void move(const QPoint&) Q_DECL_OVERRIDE { }
     virtual void inputMethodStateChanged(bool editorVisible) Q_DECL_OVERRIDE;
     virtual void setTooltip(const QString&) Q_DECL_OVERRIDE { }
+    // The QtQuick view doesn't have a backbuffer of its own and doesn't need this
+    virtual void setClearColor(const QColor &) Q_DECL_OVERRIDE { }
 
 protected:
     virtual void focusInEvent(QFocusEvent *event) Q_DECL_OVERRIDE;
diff --git a/src/webengine/render_widget_host_view_qt_delegate_quickwindow.h b/src/webengine/render_widget_host_view_qt_delegate_quickwindow.h
index cda51a1ab..a4b08482f 100644
--- a/src/webengine/render_widget_host_view_qt_delegate_quickwindow.h
+++ b/src/webengine/render_widget_host_view_qt_delegate_quickwindow.h
@@ -73,6 +73,7 @@ public:
     virtual void move(const QPoint &screenPos) Q_DECL_OVERRIDE;
     virtual void inputMethodStateChanged(bool) Q_DECL_OVERRIDE {}
     virtual void setTooltip(const QString &tooltip) Q_DECL_OVERRIDE;
+    virtual void setClearColor(const QColor &) Q_DECL_OVERRIDE { }
 
 private:
     QScopedPointer<RenderWidgetHostViewQtDelegate> m_realDelegate;
diff --git a/src/webenginewidgets/api/qwebenginepage.cpp b/src/webenginewidgets/api/qwebenginepage.cpp
index f93227297..e7d4e60e5 100644
--- a/src/webenginewidgets/api/qwebenginepage.cpp
+++ b/src/webenginewidgets/api/qwebenginepage.cpp
@@ -87,6 +87,7 @@ QWebEnginePagePrivate::QWebEnginePagePrivate(QWebEngineProfile *_profile)
     , view(0)
     , isLoading(false)
     , scriptCollection(new QWebEngineScriptCollectionPrivate(browserContextAdapter()->userScriptController(), adapter.data()))
+    , m_backgroundColor(Qt::white)
 {
     memset(actions, 0, sizeof(actions));
 }
@@ -149,6 +150,11 @@ qreal QWebEnginePagePrivate::dpiScale() const
     return 1.0;
 }
 
+QColor QWebEnginePagePrivate::backgroundColor() const
+{
+    return m_backgroundColor;
+}
+
 void QWebEnginePagePrivate::loadStarted(const QUrl &provisionalUrl, bool isErrorPage)
 {
     Q_UNUSED(provisionalUrl);
@@ -433,6 +439,33 @@ void QWebEnginePage::setWebChannel(QWebChannel *channel)
     d->adapter->setWebChannel(channel);
 }
 
+/*!
+    \property QWebEnginePage::backgroundColor
+    \brief the page's background color, behing the document's body.
+    \since 5.6
+
+    You can set it to Qt::transparent or to a translucent
+    color to see through the document, or you can set this color to match your
+    web content in an hybrid app to prevent the white flashes that may appear
+    during loading.
+
+    The default value is white.
+*/
+QColor QWebEnginePage::backgroundColor() const
+{
+    Q_D(const QWebEnginePage);
+    return d->m_backgroundColor;
+}
+
+void QWebEnginePage::setBackgroundColor(const QColor &color)
+{
+    Q_D(QWebEnginePage);
+    if (d->m_backgroundColor == color)
+        return;
+    d->m_backgroundColor = color;
+    d->adapter->backgroundColorChanged();
+}
+
 void QWebEnginePage::setView(QWidget *view)
 {
     QWebEngineViewPrivate::bind(qobject_cast<QWebEngineView*>(view), this);
diff --git a/src/webenginewidgets/api/qwebenginepage.h b/src/webenginewidgets/api/qwebenginepage.h
index f4d0cd18d..471fd7290 100644
--- a/src/webenginewidgets/api/qwebenginepage.h
+++ b/src/webenginewidgets/api/qwebenginepage.h
@@ -68,6 +68,7 @@ class QWEBENGINEWIDGETS_EXPORT QWebEnginePage : public QObject {
     Q_PROPERTY(QString title READ title)
     Q_PROPERTY(QUrl url READ url WRITE setUrl)
     Q_PROPERTY(QUrl iconUrl READ iconUrl)
+    Q_PROPERTY(QColor backgroundColor READ backgroundColor WRITE setBackgroundColor)
 
 public:
     enum WebAction {
@@ -223,6 +224,8 @@ public:
 
     QWebChannel *webChannel() const;
     void setWebChannel(QWebChannel *);
+    QColor backgroundColor() const;
+    void setBackgroundColor(const QColor &color);
 
 Q_SIGNALS:
     void loadStarted();
diff --git a/src/webenginewidgets/api/qwebenginepage_p.h b/src/webenginewidgets/api/qwebenginepage_p.h
index a5ede1a8e..a9449007d 100644
--- a/src/webenginewidgets/api/qwebenginepage_p.h
+++ b/src/webenginewidgets/api/qwebenginepage_p.h
@@ -75,6 +75,7 @@ public:
     virtual void selectionChanged() Q_DECL_OVERRIDE;
     virtual QRectF viewportRect() const Q_DECL_OVERRIDE;
     virtual qreal dpiScale() const Q_DECL_OVERRIDE;
+    virtual QColor backgroundColor() const Q_DECL_OVERRIDE;
     virtual void loadStarted(const QUrl &provisionalUrl, bool isErrorPage = false) Q_DECL_OVERRIDE;
     virtual void loadCommitted() Q_DECL_OVERRIDE;
     virtual void loadVisuallyCommitted() Q_DECL_OVERRIDE { }
@@ -127,6 +128,7 @@ public:
     QtWebEngineCore::WebEngineContextMenuData m_menuData;
     bool isLoading;
     QWebEngineScriptCollection scriptCollection;
+    QColor m_backgroundColor;
 
     mutable QtWebEngineCore::CallbackDirectory m_callbacks;
     mutable QAction *actions[QWebEnginePage::WebActionCount];
diff --git a/src/webenginewidgets/render_widget_host_view_qt_delegate_widget.cpp b/src/webenginewidgets/render_widget_host_view_qt_delegate_widget.cpp
index dba37cea7..76ca8d354 100644
--- a/src/webenginewidgets/render_widget_host_view_qt_delegate_widget.cpp
+++ b/src/webenginewidgets/render_widget_host_view_qt_delegate_widget.cpp
@@ -59,6 +59,7 @@ RenderWidgetHostViewQtDelegateWidget::RenderWidgetHostViewQtDelegateWidget(Rende
     , m_rootNode(new QSGRootNode)
     , m_sgEngine(new QSGEngine)
     , m_isPopup(false)
+    , m_clearColor(Qt::white)
 {
     setFocusPolicy(Qt::StrongFocus);
 
@@ -218,6 +219,19 @@ void RenderWidgetHostViewQtDelegateWidget::setTooltip(const QString &tooltip)
     setToolTip(wrappedTip);
 }
 
+void RenderWidgetHostViewQtDelegateWidget::setClearColor(const QColor &color)
+{
+    m_clearColor = color;
+    // QOpenGLWidget is usually blended by punching holes into widgets
+    // above it to simulate the visual stacking order. If we want it to be
+    // transparent we have to throw away the proper stacking order and always
+    // blend the complete normal widgets backing store under it.
+    bool isTranslucent = color.alpha() < 255;
+    setAttribute(Qt::WA_AlwaysStackOnTop, isTranslucent);
+    setAttribute(Qt::WA_OpaquePaintEvent, !isTranslucent);
+    update();
+}
+
 QVariant RenderWidgetHostViewQtDelegateWidget::inputMethodQuery(Qt::InputMethodQuery query) const
 {
     return m_client->inputMethodQuery(query);
@@ -270,7 +284,7 @@ void RenderWidgetHostViewQtDelegateWidget::initializeGL()
     m_sgEngine->initialize(QOpenGLContext::currentContext());
     m_sgRenderer.reset(m_sgEngine->createRenderer());
     m_sgRenderer->setRootNode(m_rootNode.data());
-    m_sgRenderer->setClearColor(Qt::white);
+    m_sgRenderer->setClearColor(m_clearColor);
 }
 
 void RenderWidgetHostViewQtDelegateWidget::paintGL()
diff --git a/src/webenginewidgets/render_widget_host_view_qt_delegate_widget.h b/src/webenginewidgets/render_widget_host_view_qt_delegate_widget.h
index d0dfdc689..d228bd487 100644
--- a/src/webenginewidgets/render_widget_host_view_qt_delegate_widget.h
+++ b/src/webenginewidgets/render_widget_host_view_qt_delegate_widget.h
@@ -78,6 +78,7 @@ public:
     virtual void move(const QPoint &screenPos) Q_DECL_OVERRIDE;
     virtual void inputMethodStateChanged(bool editorVisible) Q_DECL_OVERRIDE;
     virtual void setTooltip(const QString &tooltip) Q_DECL_OVERRIDE;
+    virtual void setClearColor(const QColor &color) Q_DECL_OVERRIDE;
 
 protected:
     bool event(QEvent *event) Q_DECL_OVERRIDE;
@@ -98,6 +99,7 @@ private:
     QScopedPointer<QSGEngine> m_sgEngine;
     QScopedPointer<QSGAbstractRenderer> m_sgRenderer;
     bool m_isPopup;
+    QColor m_clearColor;
     QList<QMetaObject::Connection> m_windowConnections;
 };