Move scenegraph handling out of core

Replace Display{Producer,Consumer,FrameSink} with the new classes
Compositor and Compositor::Observer.

The Compositor subclasses are implemented by the OutputSurfaces,
replacing DisplayProducer in this role. Unlike DisplayProducer, the
new classes do not use QtQuick scenegraph types, but rather give
access to the software QImage or OpenGL texture directly.

The connection to the "other half" is simplified by replacing
DisplayConsumer with Compositor::Observer, which is no longer
implemented by RenderWidgetHostViewQt, but directly by its delegates
in the quick and widgets libraries. RenderWidgetHostViewQt now only
provides the delegate with a Compositor::Id which is used to connect
the corresponding Compositor and Observer.

The delegates are responsible for generating QtQuick scenegraph nodes
from the information provided by the Compositor subclasses.

Behavior with software and old OpenGL scenegraph backends is
unchanged: both continue to work. As for the RHI scenegraph backend,
the code here is correct but nonetheless not working: changes are
needed in qtbase to make RHI use the global share context for its
OpenGL context.

Fixes: QTBUG-78682
Change-Id: I837da8860a18ec366ed33f6ecc44c147245e1101
Reviewed-by: Michal Klocek <michal.klocek@qt.io>

17 files changed, 517 insertions, 597 deletions

diff --git a/src/core/compositor/compositor.cpp b/src/core/compositor/compositor.cpp
new file mode 100644
index 000000000..c45c02844
--- /dev/null
+++ b/src/core/compositor/compositor.cpp
@@ -0,0 +1,215 @@
+/****************************************************************************
+**
+** Copyright (C) 2020 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the QtWebEngine module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 3 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL3 included in the
+** packaging of this file. Please review the following information to
+** ensure the GNU Lesser General Public License version 3 requirements
+** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 2.0 or (at your option) the GNU General
+** Public license version 3 or any later version approved by the KDE Free
+** Qt Foundation. The licenses are as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
+** included in the packaging of this file. Please review the following
+** information to ensure the GNU General Public License requirements will
+** be met: https://www.gnu.org/licenses/gpl-2.0.html and
+** https://www.gnu.org/licenses/gpl-3.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include "compositor.h"
+
+#include "base/memory/ref_counted.h"
+#include "components/viz/common/surfaces/frame_sink_id.h"
+
+#include <QHash>
+#include <QImage>
+#include <QMutex>
+
+namespace QtWebEngineCore {
+
+// Compositor::Id
+
+Compositor::Id::Id(viz::FrameSinkId fid) : client_id(fid.client_id()), sink_id(fid.sink_id()) { }
+
+static size_t qHash(Compositor::Id id, size_t seed = 0)
+{
+    QtPrivate::QHashCombine hasher;
+    seed = hasher(seed, id.client_id);
+    seed = hasher(seed, id.sink_id);
+    return seed;
+}
+
+static bool operator==(Compositor::Id id1, Compositor::Id id2)
+{
+    return id1.client_id == id2.client_id && id1.sink_id == id2.sink_id;
+}
+
+// Compositor::Binding and Compositor::Bindings
+
+struct Compositor::Binding
+{
+    const Id id;
+    Compositor *compositor = nullptr;
+    Observer *observer = nullptr;
+
+    Binding(Id id) : id(id) { }
+    ~Binding();
+};
+
+class Compositor::BindingMap
+{
+public:
+    void lock() { m_mutex.lock(); }
+
+    void unlock() { m_mutex.unlock(); }
+
+    Binding *findOrCreate(Id id)
+    {
+        auto it = m_map.find(id);
+        if (it == m_map.end())
+            it = m_map.insert(id, new Binding(id));
+        return *it;
+    }
+
+    void remove(Id id) { m_map.remove(id); }
+
+private:
+    QMutex m_mutex;
+    QHash<Id, Binding *> m_map;
+} static g_bindings;
+
+Compositor::Binding::~Binding()
+{
+    g_bindings.remove(id);
+}
+
+// Compositor::Observer
+
+void Compositor::Observer::bind(Id id)
+{
+    DCHECK(!m_binding);
+    g_bindings.lock();
+    m_binding = g_bindings.findOrCreate(id);
+    DCHECK(!m_binding->observer);
+    m_binding->observer = this;
+    g_bindings.unlock();
+}
+
+void Compositor::Observer::unbind()
+{
+    DCHECK(m_binding);
+    g_bindings.lock();
+    m_binding->observer = nullptr;
+    if (m_binding->compositor == nullptr)
+        delete m_binding;
+    m_binding = nullptr;
+    g_bindings.unlock();
+}
+
+Compositor::Handle<Compositor> Compositor::Observer::compositor()
+{
+    if (!m_binding)
+        return nullptr;
+    g_bindings.lock();
+    if (m_binding->compositor)
+        return m_binding->compositor; // delay unlock
+    g_bindings.unlock();
+    return nullptr;
+}
+
+// Compositor
+
+void Compositor::bind(Id id)
+{
+    DCHECK(!m_binding);
+    g_bindings.lock();
+    m_binding = g_bindings.findOrCreate(id);
+    DCHECK(!m_binding->compositor);
+    m_binding->compositor = this;
+    g_bindings.unlock();
+}
+
+void Compositor::unbind()
+{
+    DCHECK(m_binding);
+    g_bindings.lock();
+    m_binding->compositor = nullptr;
+    if (m_binding->observer == nullptr)
+        delete m_binding;
+    m_binding = nullptr;
+    g_bindings.unlock();
+}
+
+Compositor::Handle<Compositor::Observer> Compositor::observer()
+{
+    if (!m_binding)
+        return nullptr;
+    g_bindings.lock();
+    if (m_binding->observer)
+        return m_binding->observer; // delay unlock
+    g_bindings.unlock();
+    return nullptr;
+}
+
+float Compositor::devicePixelRatio()
+{
+    Q_UNREACHABLE();
+    return 1;
+}
+
+QImage Compositor::image()
+{
+    Q_UNREACHABLE();
+    return {};
+}
+
+void Compositor::waitForTexture()
+{
+    Q_UNREACHABLE();
+}
+
+int Compositor::textureId()
+{
+    Q_UNREACHABLE();
+    return 0;
+}
+
+QSize Compositor::textureSize()
+{
+    Q_UNREACHABLE();
+    return {};
+}
+
+bool Compositor::hasAlphaChannel()
+{
+    Q_UNREACHABLE();
+    return false;
+}
+
+// static
+void Compositor::unlockBindings()
+{
+    g_bindings.unlock();
+}
+} // namespace QtWebEngineCore
diff --git a/src/core/compositor/compositor.h b/src/core/compositor/compositor.h
new file mode 100644
index 000000000..d10cf2ef6
--- /dev/null
+++ b/src/core/compositor/compositor.h
@@ -0,0 +1,185 @@
+/****************************************************************************
+**
+** Copyright (C) 2020 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the QtWebEngine module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 3 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL3 included in the
+** packaging of this file. Please review the following information to
+** ensure the GNU Lesser General Public License version 3 requirements
+** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 2.0 or (at your option) the GNU General
+** Public license version 3 or any later version approved by the KDE Free
+** Qt Foundation. The licenses are as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
+** included in the packaging of this file. Please review the following
+** information to ensure the GNU General Public License requirements will
+** be met: https://www.gnu.org/licenses/gpl-2.0.html and
+** https://www.gnu.org/licenses/gpl-3.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#ifndef COMPOSITOR_H
+#define COMPOSITOR_H
+
+#include "qtwebenginecoreglobal_p.h"
+
+QT_BEGIN_NAMESPACE
+class QImage;
+class QSize;
+QT_END_NAMESPACE
+
+namespace viz {
+class FrameSinkId;
+} // namespace viz
+
+namespace QtWebEngineCore {
+
+// Produces composited frames for display.
+//
+// Used by quick/widgets libraries for accessing the frame and
+// controlling frame swapping. Must be cast to a subclass to access
+// the frame as QImage or OpenGL texture, etc.
+class Q_WEBENGINECORE_PRIVATE_EXPORT Compositor
+{
+    struct Binding;
+
+public:
+    // Identifies the implementation type.
+    enum class Type {
+        Software,
+        OpenGL,
+    };
+
+    // Identifies a compositor.
+    //
+    // The purpose of assigning ids to compositors is to allow the
+    // corresponding observer to be registered before the compositor
+    // itself is created, which is necessary since the creation
+    // happens on a different thread in the depths of viz.
+    //
+    // (Maps to viz::FrameSinkId internally).
+    struct Id
+    {
+        quint32 client_id;
+        quint32 sink_id;
+
+        Id(viz::FrameSinkId);
+    };
+
+    // Pointer to Compositor or Observer that holds a lock to prevent
+    // either from being unbound and destroyed.
+    template<typename T>
+    class Handle
+    {
+    public:
+        Handle(std::nullptr_t) : m_data(nullptr) { }
+        Handle(T *data) : m_data(data) { }
+        Handle(Handle &&that) : m_data(that.m_data) { that.m_data = nullptr; }
+        ~Handle()
+        {
+            if (m_data)
+                Compositor::unlockBindings();
+        }
+        T *operator->() const { return m_data; }
+        T &operator*() const { return *m_data; }
+        explicit operator bool() const { return m_data; }
+
+    private:
+        T *m_data;
+    };
+
+    // Observes the compositor corresponding to the given id.
+    //
+    // Only one observer can exist per compositor.
+    class Q_WEBENGINECORE_PRIVATE_EXPORT Observer
+    {
+    public:
+        // Binding to compositor
+        void bind(Id id);
+        void unbind();
+
+        // Compositor if bound
+        Handle<Compositor> compositor();
+
+        // There's a new frame ready, time to swapFrame().
+        virtual void readyToSwap() = 0;
+
+    protected:
+        Observer() = default;
+        ~Observer() = default;
+
+    private:
+        Binding *m_binding = nullptr;
+    };
+
+    // Type determines which methods can be called.
+    Type type() const { return m_type; }
+
+    // Binding to observer.
+    void bind(Id id);
+    void unbind();
+
+    // Observer if bound.
+    Handle<Observer> observer();
+
+    // Update to next frame if possible.
+    virtual void swapFrame() = 0;
+
+    // Ratio of pixels to DIPs.
+    //
+    // Don't use the devicePixelRatio of QImage, it's always 1.
+    virtual float devicePixelRatio();
+
+    // (Software) QImage of the frame.
+    //
+    // This is a big image so we should try not to make copies of it.
+    // In particular, the client should drop its QImage reference
+    // before calling swapFrame(), otherwise each swap will cause a
+    // detach.
+    virtual QImage image();
+
+    // (OpenGL) Wait on texture fence in Qt's current OpenGL context.
+    virtual void waitForTexture();
+
+    // (OpenGL) Properties of the current frame.
+    virtual int textureId();
+    virtual QSize textureSize();
+    virtual bool hasAlphaChannel();
+
+protected:
+    Compositor(Type type) : m_type(type) { }
+    ~Compositor() = default;
+
+private:
+    template<typename T>
+    friend class Handle;
+
+    class BindingMap;
+    static void unlockBindings();
+
+    const Type m_type;
+    Binding *m_binding = nullptr;
+};
+
+} // namespace QtWebEngineCore
+
+#endif // !COMPOSITOR_H
diff --git a/src/core/compositor/display_consumer.h b/src/core/compositor/display_consumer.h
deleted file mode 100644
index d220088ad..000000000
--- a/src/core/compositor/display_consumer.h
+++ /dev/null
@@ -1,62 +0,0 @@
-/****************************************************************************
-**
-** Copyright (C) 2019 The Qt Company Ltd.
-** Contact: https://www.qt.io/licensing/
-**
-** This file is part of the QtWebEngine module of the Qt Toolkit.
-**
-** $QT_BEGIN_LICENSE:LGPL$
-** Commercial License Usage
-** Licensees holding valid commercial Qt licenses may use this file in
-** accordance with the commercial license agreement provided with the
-** Software or, alternatively, in accordance with the terms contained in
-** a written agreement between you and The Qt Company. For licensing terms
-** and conditions see https://www.qt.io/terms-conditions. For further
-** information use the contact form at https://www.qt.io/contact-us.
-**
-** GNU Lesser General Public License Usage
-** Alternatively, this file may be used under the terms of the GNU Lesser
-** General Public License version 3 as published by the Free Software
-** Foundation and appearing in the file LICENSE.LGPL3 included in the
-** packaging of this file. Please review the following information to
-** ensure the GNU Lesser General Public License version 3 requirements
-** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
-**
-** GNU General Public License Usage
-** Alternatively, this file may be used under the terms of the GNU
-** General Public License version 2.0 or (at your option) the GNU General
-** Public license version 3 or any later version approved by the KDE Free
-** Qt Foundation. The licenses are as published by the Free Software
-** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
-** included in the packaging of this file. Please review the following
-** information to ensure the GNU General Public License requirements will
-** be met: https://www.gnu.org/licenses/gpl-2.0.html and
-** https://www.gnu.org/licenses/gpl-3.0.html.
-**
-** $QT_END_LICENSE$
-**
-****************************************************************************/
-
-#ifndef DISPLAY_CONSUMER_H
-#define DISPLAY_CONSUMER_H
-
-#include "qtwebenginecoreglobal_p.h"
-
-namespace QtWebEngineCore {
-
-// Receives composited frames for display.
-class DisplayConsumer
-{
-public:
-    // Schedule a call to updatePaintNode soon.
-    //
-    // Called on the consumer thread.
-    virtual void scheduleUpdate() = 0;
-
-protected:
-    ~DisplayConsumer() {}
-};
-
-} // namespace QtWebEngineCore
-
-#endif // !DISPLAY_CONSUMER_H
diff --git a/src/core/compositor/display_frame_sink.cpp b/src/core/compositor/display_frame_sink.cpp
deleted file mode 100644
index 945600299..000000000
--- a/src/core/compositor/display_frame_sink.cpp
+++ /dev/null
@@ -1,140 +0,0 @@
-/****************************************************************************
-**
-** Copyright (C) 2019 The Qt Company Ltd.
-** Contact: https://www.qt.io/licensing/
-**
-** This file is part of the QtWebEngine module of the Qt Toolkit.
-**
-** $QT_BEGIN_LICENSE:LGPL$
-** Commercial License Usage
-** Licensees holding valid commercial Qt licenses may use this file in
-** accordance with the commercial license agreement provided with the
-** Software or, alternatively, in accordance with the terms contained in
-** a written agreement between you and The Qt Company. For licensing terms
-** and conditions see https://www.qt.io/terms-conditions. For further
-** information use the contact form at https://www.qt.io/contact-us.
-**
-** GNU Lesser General Public License Usage
-** Alternatively, this file may be used under the terms of the GNU Lesser
-** General Public License version 3 as published by the Free Software
-** Foundation and appearing in the file LICENSE.LGPL3 included in the
-** packaging of this file. Please review the following information to
-** ensure the GNU Lesser General Public License version 3 requirements
-** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
-**
-** GNU General Public License Usage
-** Alternatively, this file may be used under the terms of the GNU
-** General Public License version 2.0 or (at your option) the GNU General
-** Public license version 3 or any later version approved by the KDE Free
-** Qt Foundation. The licenses are as published by the Free Software
-** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
-** included in the packaging of this file. Please review the following
-** information to ensure the GNU General Public License requirements will
-** be met: https://www.gnu.org/licenses/gpl-2.0.html and
-** https://www.gnu.org/licenses/gpl-3.0.html.
-**
-** $QT_END_LICENSE$
-**
-****************************************************************************/
-
-#include "display_frame_sink.h"
-
-#include <QMap>
-
-namespace QtWebEngineCore {
-
-namespace {
-
-class DisplayFrameSinkMap
-{
-public:
-    static DisplayFrameSinkMap *instance()
-    {
-        static DisplayFrameSinkMap map;
-        return &map;
-    }
-
-    scoped_refptr<DisplayFrameSink> findOrCreate(viz::FrameSinkId frameSinkId)
-    {
-        QMutexLocker locker(&m_mutex);
-        auto it = m_map.find(frameSinkId);
-        if (it == m_map.end())
-            it = m_map.insert(frameSinkId, new DisplayFrameSink(frameSinkId));
-        return *it;
-    }
-
-    void remove(viz::FrameSinkId frameSinkId)
-    {
-        QMutexLocker locker(&m_mutex);
-        m_map.remove(frameSinkId);
-    }
-
-private:
-    mutable QMutex m_mutex;
-    QMap<viz::FrameSinkId, DisplayFrameSink *> m_map;
-};
-
-} // namespace
-
-// static
-scoped_refptr<DisplayFrameSink> DisplayFrameSink::findOrCreate(viz::FrameSinkId frameSinkId)
-{
-    return DisplayFrameSinkMap::instance()->findOrCreate(frameSinkId);
-}
-
-DisplayFrameSink::DisplayFrameSink(viz::FrameSinkId frameSinkId)
-    : m_frameSinkId(frameSinkId)
-{
-    DCHECK(m_frameSinkId.is_valid());
-}
-
-DisplayFrameSink::~DisplayFrameSink()
-{
-    DisplayFrameSinkMap::instance()->remove(m_frameSinkId);
-}
-
-void DisplayFrameSink::connect(DisplayConsumer *consumer)
-{
-    QMutexLocker locker(&m_mutex);
-    DCHECK(m_consumer == nullptr);
-    m_consumer = consumer;
-}
-
-void DisplayFrameSink::connect(DisplayProducer *producer)
-{
-    QMutexLocker locker(&m_mutex);
-    DCHECK(m_producer == nullptr);
-    m_producer = producer;
-}
-
-void DisplayFrameSink::disconnect(DisplayConsumer *consumer)
-{
-    QMutexLocker locker(&m_mutex);
-    DCHECK(m_consumer == consumer);
-    m_consumer = nullptr;
-}
-
-void DisplayFrameSink::disconnect(DisplayProducer *producer)
-{
-    QMutexLocker locker(&m_mutex);
-    DCHECK(m_producer == producer);
-    m_producer = nullptr;
-}
-
-void DisplayFrameSink::scheduleUpdate()
-{
-    QMutexLocker locker(&m_mutex);
-    if (m_consumer)
-        m_consumer->scheduleUpdate();
-}
-
-QSGNode *DisplayFrameSink::updatePaintNode(QSGNode *oldNode, RenderWidgetHostViewQtDelegate *delegate)
-{
-    QMutexLocker locker(&m_mutex);
-    QSGNode *newNode = oldNode;
-    if (m_producer)
-        newNode = m_producer->updatePaintNode(oldNode, delegate);
-    return newNode;
-}
-
-} // namespace QtWebEngineCore
diff --git a/src/core/compositor/display_frame_sink.h b/src/core/compositor/display_frame_sink.h
deleted file mode 100644
index f620dc4f2..000000000
--- a/src/core/compositor/display_frame_sink.h
+++ /dev/null
@@ -1,77 +0,0 @@
-/****************************************************************************
-**
-** Copyright (C) 2019 The Qt Company Ltd.
-** Contact: https://www.qt.io/licensing/
-**
-** This file is part of the QtWebEngine module of the Qt Toolkit.
-**
-** $QT_BEGIN_LICENSE:LGPL$
-** Commercial License Usage
-** Licensees holding valid commercial Qt licenses may use this file in
-** accordance with the commercial license agreement provided with the
-** Software or, alternatively, in accordance with the terms contained in
-** a written agreement between you and The Qt Company. For licensing terms
-** and conditions see https://www.qt.io/terms-conditions. For further
-** information use the contact form at https://www.qt.io/contact-us.
-**
-** GNU Lesser General Public License Usage
-** Alternatively, this file may be used under the terms of the GNU Lesser
-** General Public License version 3 as published by the Free Software
-** Foundation and appearing in the file LICENSE.LGPL3 included in the
-** packaging of this file. Please review the following information to
-** ensure the GNU Lesser General Public License version 3 requirements
-** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
-**
-** GNU General Public License Usage
-** Alternatively, this file may be used under the terms of the GNU
-** General Public License version 2.0 or (at your option) the GNU General
-** Public license version 3 or any later version approved by the KDE Free
-** Qt Foundation. The licenses are as published by the Free Software
-** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
-** included in the packaging of this file. Please review the following
-** information to ensure the GNU General Public License requirements will
-** be met: https://www.gnu.org/licenses/gpl-2.0.html and
-** https://www.gnu.org/licenses/gpl-3.0.html.
-**
-** $QT_END_LICENSE$
-**
-****************************************************************************/
-
-#ifndef DISPLAY_FRAME_SINK_H
-#define DISPLAY_FRAME_SINK_H
-
-#include "display_consumer.h"
-#include "display_producer.h"
-
-#include "base/memory/ref_counted.h"
-#include "base/memory/scoped_refptr.h"
-#include "components/viz/common/surfaces/frame_sink_id.h"
-
-#include <QMutex>
-
-namespace QtWebEngineCore {
-
-// Connects a DisplayConsumer with a DisplayProducer.
-class DisplayFrameSink final : public base::RefCountedThreadSafe<DisplayFrameSink>
-{
-public:
-    static scoped_refptr<DisplayFrameSink> findOrCreate(viz::FrameSinkId frameSinkId);
-    DisplayFrameSink(viz::FrameSinkId frameSinkId);
-    ~DisplayFrameSink();
-    void connect(DisplayConsumer *consumer);
-    void connect(DisplayProducer *producer);
-    void disconnect(DisplayConsumer *consumer);
-    void disconnect(DisplayProducer *producer);
-    void scheduleUpdate();
-    QSGNode *updatePaintNode(QSGNode *oldNode, RenderWidgetHostViewQtDelegate *delegate);
-
-private:
-    const viz::FrameSinkId m_frameSinkId;
-    mutable QMutex m_mutex;
-    DisplayProducer *m_producer = nullptr;
-    DisplayConsumer *m_consumer = nullptr;
-};
-
-} // namespace QtWebEngineCore
-
-#endif // !DISPLAY_FRAME_SINK_H
diff --git a/src/core/compositor/display_gl_output_surface.cpp b/src/core/compositor/display_gl_output_surface.cpp
index 4f63e5b69..f736bba79 100644
--- a/src/core/compositor/display_gl_output_surface.cpp
+++ b/src/core/compositor/display_gl_output_surface.cpp
@@ -39,6 +39,8 @@
 
 #include "display_gl_output_surface.h"
 
+#include "type_conversion.h"
+
 #include "base/threading/thread_task_runner_handle.h"
 #include "components/viz/service/display/display.h"
 #include "components/viz/service/display/output_surface_frame.h"
@@ -51,8 +53,10 @@
 
 namespace QtWebEngineCore {
 
-DisplayGLOutputSurface::DisplayGLOutputSurface(scoped_refptr<viz::VizProcessContextProvider> contextProvider)
+DisplayGLOutputSurface::DisplayGLOutputSurface(
+        scoped_refptr<viz::VizProcessContextProvider> contextProvider)
     : OutputSurface(contextProvider)
+    , Compositor(Compositor::Type::OpenGL)
     , m_commandBuffer(contextProvider->command_buffer())
     , m_gl(contextProvider->ContextGL())
     , m_vizContextProvider(contextProvider)
@@ -63,18 +67,16 @@ DisplayGLOutputSurface::DisplayGLOutputSurface(scoped_refptr<viz::VizProcessCont
 
 DisplayGLOutputSurface::~DisplayGLOutputSurface()
 {
+    unbind();
     m_vizContextProvider->SetUpdateVSyncParametersCallback(viz::UpdateVSyncParametersCallback());
     m_gl->DeleteFramebuffers(1, &m_fboId);
-    if (m_sink)
-        m_sink->disconnect(this);
 }
 
 // Called from viz::Display::Initialize.
 void DisplayGLOutputSurface::BindToClient(viz::OutputSurfaceClient *client)
 {
     m_display = static_cast<viz::Display *>(client);
-    m_sink = DisplayFrameSink::findOrCreate(m_display->frame_sink_id());
-    m_sink->connect(this);
+    bind(m_display->frame_sink_id());
 }
 
 // Triggered by ui::Compositor::SetVisible(true).
@@ -211,7 +213,8 @@ void DisplayGLOutputSurface::swapBuffersOnGpuThread(unsigned int id, std::unique
         m_middleBuffer->fence = CompositorResourceFence::create(std::move(fence));
     }
 
-    m_sink->scheduleUpdate();
+    if (auto obs = observer())
+        obs->readyToSwap();
 }
 
 void DisplayGLOutputSurface::swapBuffersOnVizThread()
@@ -295,4 +298,44 @@ gfx::OverlayTransform DisplayGLOutputSurface::GetDisplayTransform()
     return gfx::OVERLAY_TRANSFORM_NONE;
 }
 
+void DisplayGLOutputSurface::swapFrame()
+{
+    QMutexLocker locker(&m_mutex);
+    if (m_middleBuffer && m_middleBuffer->serviceId) {
+        std::swap(m_middleBuffer, m_frontBuffer);
+        m_taskRunner->PostTask(FROM_HERE,
+                               base::BindOnce(&DisplayGLOutputSurface::swapBuffersOnVizThread,
+                                              base::Unretained(this)));
+        m_taskRunner.reset();
+    }
+}
+
+void DisplayGLOutputSurface::waitForTexture()
+{
+    if (m_frontBuffer && m_frontBuffer->fence) {
+        m_frontBuffer->fence->wait();
+        m_frontBuffer->fence.reset();
+    }
+}
+
+int DisplayGLOutputSurface::textureId()
+{
+    return m_frontBuffer ? m_frontBuffer->serviceId : 0;
+}
+
+QSize DisplayGLOutputSurface::textureSize()
+{
+    return m_frontBuffer ? toQt(m_frontBuffer->shape.sizeInPixels) : QSize();
+}
+
+bool DisplayGLOutputSurface::hasAlphaChannel()
+{
+    return m_frontBuffer ? m_frontBuffer->shape.hasAlpha : false;
+}
+
+float DisplayGLOutputSurface::devicePixelRatio()
+{
+    return m_frontBuffer ? m_frontBuffer->shape.devicePixelRatio : 1;
+}
+
 } // namespace QtWebEngineCore
diff --git a/src/core/compositor/display_gl_output_surface.h b/src/core/compositor/display_gl_output_surface.h
index 67d987263..678d0cf5c 100644
--- a/src/core/compositor/display_gl_output_surface.h
+++ b/src/core/compositor/display_gl_output_surface.h
@@ -41,7 +41,7 @@
 #define DISPLAY_GL_OUTPUT_SURFACE_H
 
 #include "compositor_resource_fence.h"
-#include "display_frame_sink.h"
+#include "compositor.h"
 
 #include "components/viz/common/display/update_vsync_parameters_callback.h"
 #include "components/viz/service/display/output_surface.h"
@@ -49,6 +49,8 @@
 #include "gpu/command_buffer/common/mailbox.h"
 #include "gpu/command_buffer/common/sync_token.h"
 
+#include <QMutex>
+
 namespace viz {
 class Display;
 class SyntheticBeginFrameSource;
@@ -56,9 +58,7 @@ class SyntheticBeginFrameSource;
 
 namespace QtWebEngineCore {
 
-// NOTE: Some methods are defined in display_gl_output_surface_qsg.cpp due
-// to conflicts between Qt & Chromium OpenGL APIs.
-class DisplayGLOutputSurface final : public viz::OutputSurface, public DisplayProducer
+class DisplayGLOutputSurface final : public viz::OutputSurface, public Compositor
 {
 public:
     DisplayGLOutputSurface(scoped_refptr<viz::VizProcessContextProvider> contextProvider);
@@ -87,8 +87,13 @@ public:
     void SetDisplayTransformHint(gfx::OverlayTransform transform) override;
     gfx::OverlayTransform GetDisplayTransform() override;
 
-    // Overridden from DisplayProducer.
-    QSGNode *updatePaintNode(QSGNode *oldNode, RenderWidgetHostViewQtDelegate *delegate) override;
+    // Overridden from Compositor.
+    void swapFrame() override;
+    void waitForTexture() override;
+    int textureId() override;
+    QSize textureSize() override;
+    bool hasAlphaChannel() override;
+    float devicePixelRatio() override;
 
 private:
     struct Shape
@@ -135,7 +140,6 @@ private:
     mutable QMutex m_mutex;
     uint32_t m_fboId = 0;
     viz::Display *m_display = nullptr;
-    scoped_refptr<DisplayFrameSink> m_sink;
     Shape m_currentShape;
     std::unique_ptr<Buffer> m_backBuffer;
     std::unique_ptr<Buffer> m_middleBuffer;
diff --git a/src/core/compositor/display_gl_output_surface_qsg.cpp b/src/core/compositor/display_gl_output_surface_qsg.cpp
deleted file mode 100644
index 2ed24ef1d..000000000
--- a/src/core/compositor/display_gl_output_surface_qsg.cpp
+++ /dev/null
@@ -1,122 +0,0 @@
-/****************************************************************************
-**
-** Copyright (C) 2019 The Qt Company Ltd.
-** Contact: https://www.qt.io/licensing/
-**
-** This file is part of the QtWebEngine module of the Qt Toolkit.
-**
-** $QT_BEGIN_LICENSE:LGPL$
-** Commercial License Usage
-** Licensees holding valid commercial Qt licenses may use this file in
-** accordance with the commercial license agreement provided with the
-** Software or, alternatively, in accordance with the terms contained in
-** a written agreement between you and The Qt Company. For licensing terms
-** and conditions see https://www.qt.io/terms-conditions. For further
-** information use the contact form at https://www.qt.io/contact-us.
-**
-** GNU Lesser General Public License Usage
-** Alternatively, this file may be used under the terms of the GNU Lesser
-** General Public License version 3 as published by the Free Software
-** Foundation and appearing in the file LICENSE.LGPL3 included in the
-** packaging of this file. Please review the following information to
-** ensure the GNU Lesser General Public License version 3 requirements
-** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
-**
-** GNU General Public License Usage
-** Alternatively, this file may be used under the terms of the GNU
-** General Public License version 2.0 or (at your option) the GNU General
-** Public license version 3 or any later version approved by the KDE Free
-** Qt Foundation. The licenses are as published by the Free Software
-** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
-** included in the packaging of this file. Please review the following
-** information to ensure the GNU General Public License requirements will
-** be met: https://www.gnu.org/licenses/gpl-2.0.html and
-** https://www.gnu.org/licenses/gpl-3.0.html.
-**
-** $QT_END_LICENSE$
-**
-****************************************************************************/
-
-#include "display_gl_output_surface.h"
-
-#include "compositor_resource_fence.h"
-#include "render_widget_host_view_qt_delegate.h"
-#include "type_conversion.h"
-
-#include <QOpenGLFunctions>
-#include <QSGImageNode>
-#include <QSGTexture>
-
-namespace QtWebEngineCore {
-
-class DisplayGLOutputSurface::Texture final : public QSGTexture
-{
-public:
-    Texture(uint32_t id, QSize sizeInPixels, bool hasAlphaChannel, scoped_refptr<CompositorResourceFence> fence)
-        : m_id(id)
-        , m_sizeInPixels(sizeInPixels)
-        , m_hasAlphaChannel(hasAlphaChannel)
-        , m_fence(std::move(fence))
-    {
-    }
-
-    // QSGTexture:
-    int textureId() const override { return m_id; }
-    QSize textureSize() const override { return m_sizeInPixels; }
-    bool hasAlphaChannel() const override { return m_hasAlphaChannel; }
-    bool hasMipmaps() const override { return false; }
-    void bind() override
-    {
-        if (m_fence) {
-            m_fence->wait();
-            m_fence.reset();
-        }
-
-        QOpenGLContext *context = QOpenGLContext::currentContext();
-        QOpenGLFunctions *funcs = context->functions();
-        funcs->glBindTexture(GL_TEXTURE_2D, m_id);
-    }
-    int comparisonKey() const override { return m_id; }
-
-private:
-    uint32_t m_id;
-    QSize m_sizeInPixels;
-    bool m_hasAlphaChannel;
-    scoped_refptr<CompositorResourceFence> m_fence;
-};
-
-QSGNode *DisplayGLOutputSurface::updatePaintNode(QSGNode *oldNode, RenderWidgetHostViewQtDelegate *delegate)
-{
-    {
-        QMutexLocker locker(&m_mutex);
-        if (m_middleBuffer && m_middleBuffer->serviceId) {
-            std::swap(m_middleBuffer, m_frontBuffer);
-            m_taskRunner->PostTask(
-                    FROM_HERE,
-                    base::BindOnce(&DisplayGLOutputSurface::swapBuffersOnVizThread, base::Unretained(this)));
-            m_taskRunner.reset();
-        }
-    }
-
-    if (!m_frontBuffer)
-        return oldNode;
-
-    auto node = static_cast<QSGImageNode *>(oldNode);
-    if (!node)
-        node = delegate->createImageNode();
-
-    QSize sizeInPixels = toQt(m_frontBuffer->shape.sizeInPixels);
-    QSizeF sizeInDips = QSizeF(sizeInPixels) / m_frontBuffer->shape.devicePixelRatio;
-    QRectF rectInDips(QPointF(0, 0), sizeInDips);
-    node->setRect(rectInDips);
-    node->setOwnsTexture(true);
-    node->setTexture(new Texture(m_frontBuffer->serviceId,
-                                 sizeInPixels,
-                                 m_frontBuffer->shape.hasAlpha,
-                                 m_frontBuffer->fence));
-    node->setTextureCoordinatesTransform(QSGImageNode::MirrorVertically);
-
-    return node;
-}
-
-} // namespace QtWebEngineCore
diff --git a/src/core/compositor/display_producer.h b/src/core/compositor/display_producer.h
deleted file mode 100644
index 5de09d2d2..000000000
--- a/src/core/compositor/display_producer.h
+++ /dev/null
@@ -1,69 +0,0 @@
-/****************************************************************************
-**
-** Copyright (C) 2019 The Qt Company Ltd.
-** Contact: https://www.qt.io/licensing/
-**
-** This file is part of the QtWebEngine module of the Qt Toolkit.
-**
-** $QT_BEGIN_LICENSE:LGPL$
-** Commercial License Usage
-** Licensees holding valid commercial Qt licenses may use this file in
-** accordance with the commercial license agreement provided with the
-** Software or, alternatively, in accordance with the terms contained in
-** a written agreement between you and The Qt Company. For licensing terms
-** and conditions see https://www.qt.io/terms-conditions. For further
-** information use the contact form at https://www.qt.io/contact-us.
-**
-** GNU Lesser General Public License Usage
-** Alternatively, this file may be used under the terms of the GNU Lesser
-** General Public License version 3 as published by the Free Software
-** Foundation and appearing in the file LICENSE.LGPL3 included in the
-** packaging of this file. Please review the following information to
-** ensure the GNU Lesser General Public License version 3 requirements
-** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
-**
-** GNU General Public License Usage
-** Alternatively, this file may be used under the terms of the GNU
-** General Public License version 2.0 or (at your option) the GNU General
-** Public license version 3 or any later version approved by the KDE Free
-** Qt Foundation. The licenses are as published by the Free Software
-** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
-** included in the packaging of this file. Please review the following
-** information to ensure the GNU General Public License requirements will
-** be met: https://www.gnu.org/licenses/gpl-2.0.html and
-** https://www.gnu.org/licenses/gpl-3.0.html.
-**
-** $QT_END_LICENSE$
-**
-****************************************************************************/
-
-#ifndef DISPLAY_PRODUCER_H
-#define DISPLAY_PRODUCER_H
-
-#include "qtwebenginecoreglobal_p.h"
-
-QT_BEGIN_NAMESPACE
-class QSGNode;
-QT_END_NAMESPACE
-
-namespace QtWebEngineCore {
-class RenderWidgetHostViewQtDelegate;
-
-// Produces composited frames for display.
-class DisplayProducer
-{
-public:
-    // Generate scene graph nodes for the current frame.
-    //
-    // If this is a scheduled update (that is, scheduleUpdate was called
-    // earlier), then updatePaintNode will generate nodes for a new frame.
-    // Otherwise, it will just regenerate nodes for the old frame.
-    virtual QSGNode *updatePaintNode(QSGNode *oldNode, RenderWidgetHostViewQtDelegate *delegate) = 0;
-
-protected:
-    ~DisplayProducer() {}
-};
-
-} // namespace QtWebEngineCore
-
-#endif // !DISPLAY_PRODUCER_H
diff --git a/src/core/compositor/display_software_output_surface.cpp b/src/core/compositor/display_software_output_surface.cpp
index ba99799f0..b1a357615 100644
--- a/src/core/compositor/display_software_output_surface.cpp
+++ b/src/core/compositor/display_software_output_surface.cpp
@@ -39,7 +39,7 @@
 
 #include "display_software_output_surface.h"
 
-#include "display_frame_sink.h"
+#include "compositor.h"
 #include "render_widget_host_view_qt_delegate.h"
 #include "type_conversion.h"
 
@@ -49,28 +49,27 @@
 
 #include <QMutex>
 #include <QPainter>
-#include <QSGImageNode>
 
 namespace QtWebEngineCore {
 
-class DisplaySoftwareOutputSurface::Device final : public viz::SoftwareOutputDevice, public DisplayProducer
+class DisplaySoftwareOutputSurface::Device final : public viz::SoftwareOutputDevice,
+                                                   public Compositor
 {
 public:
+    Device();
     ~Device();
 
-    // Called from DisplaySoftwareOutputSurface.
-    void bind(viz::FrameSinkId frameSinkId);
-
     // Overridden from viz::SoftwareOutputDevice.
     void Resize(const gfx::Size &sizeInPixels, float devicePixelRatio) override;
     void OnSwapBuffers(SwapBuffersCallback swap_ack_callback) override;
 
-    // Overridden from DisplayProducer.
-    QSGNode *updatePaintNode(QSGNode *oldNode, RenderWidgetHostViewQtDelegate *delegate) override;
+    // Overridden from Compositor.
+    void swapFrame() override;
+    QImage image() override;
+    float devicePixelRatio() override;
 
 private:
     mutable QMutex m_mutex;
-    scoped_refptr<DisplayFrameSink> m_sink;
     float m_devicePixelRatio = 1.0;
     scoped_refptr<base::SingleThreadTaskRunner> m_taskRunner;
     SwapBuffersCallback m_swapCompletionCallback;
@@ -78,16 +77,13 @@ private:
     float m_imageDevicePixelRatio = 1.0;
 };
 
-DisplaySoftwareOutputSurface::Device::~Device()
-{
-    if (m_sink)
-        m_sink->disconnect(this);
-}
+DisplaySoftwareOutputSurface::Device::Device()
+    : Compositor(Type::Software)
+{}
 
-void DisplaySoftwareOutputSurface::Device::bind(viz::FrameSinkId frameSinkId)
+DisplaySoftwareOutputSurface::Device::~Device()
 {
-    m_sink = DisplayFrameSink::findOrCreate(frameSinkId);
-    m_sink->connect(this);
+    unbind();
 }
 
 void DisplaySoftwareOutputSurface::Device::Resize(const gfx::Size &sizeInPixels, float devicePixelRatio)
@@ -104,7 +100,8 @@ void DisplaySoftwareOutputSurface::Device::OnSwapBuffers(SwapBuffersCallback swa
     QMutexLocker locker(&m_mutex);
     m_taskRunner = base::ThreadTaskRunnerHandle::Get();
     m_swapCompletionCallback = std::move(swap_ack_callback);
-    m_sink->scheduleUpdate();
+    if (auto obs = observer())
+        obs->readyToSwap();
 }
 
 inline QImage::Format imageFormat(SkColorType colorType)
@@ -120,41 +117,41 @@ inline QImage::Format imageFormat(SkColorType colorType)
     }
 }
 
-QSGNode *DisplaySoftwareOutputSurface::Device::updatePaintNode(
-        QSGNode *oldNode, RenderWidgetHostViewQtDelegate *delegate)
+void DisplaySoftwareOutputSurface::Device::swapFrame()
 {
     QMutexLocker locker(&m_mutex);
 
-    // Delete old node to make sure refcount of m_image is at most 1.
-    delete oldNode;
-    QSGImageNode *node = delegate->createImageNode();
-
-    if (m_swapCompletionCallback) {
-        SkPixmap skPixmap;
-        surface_->peekPixels(&skPixmap);
-        QImage image(reinterpret_cast<const uchar *>(skPixmap.addr()),
-                     viewport_pixel_size_.width(), viewport_pixel_size_.height(),
-                     skPixmap.rowBytes(), imageFormat(skPixmap.colorType()));
-        if (m_image.size() == image.size()) {
-            QRect damageRect = toQt(damage_rect_);
-            QPainter painter(&m_image);
-            painter.setCompositionMode(QPainter::CompositionMode_Source);
-            painter.drawImage(damageRect, image, damageRect);
-        } else {
-            m_image = image;
-            m_image.detach();
-        }
-        m_imageDevicePixelRatio = m_devicePixelRatio;
-        m_taskRunner->PostTask(FROM_HERE, base::BindOnce(std::move(m_swapCompletionCallback), toGfx(m_image.size())));
-        m_taskRunner.reset();
+    if (!m_swapCompletionCallback)
+        return;
+
+    SkPixmap skPixmap;
+    surface_->peekPixels(&skPixmap);
+    QImage image(reinterpret_cast<const uchar *>(skPixmap.addr()), viewport_pixel_size_.width(),
+                 viewport_pixel_size_.height(), skPixmap.rowBytes(),
+                 imageFormat(skPixmap.colorType()));
+    if (m_image.size() == image.size()) {
+        QRect damageRect = toQt(damage_rect_);
+        QPainter painter(&m_image);
+        painter.setCompositionMode(QPainter::CompositionMode_Source);
+        painter.drawImage(damageRect, image, damageRect);
+    } else {
+        m_image = image;
+        m_image.detach();
     }
+    m_imageDevicePixelRatio = m_devicePixelRatio;
+    m_taskRunner->PostTask(
+            FROM_HERE, base::BindOnce(std::move(m_swapCompletionCallback), toGfx(m_image.size())));
+    m_taskRunner.reset();
+}
 
-    QSizeF sizeInDips = QSizeF(m_image.size()) / m_imageDevicePixelRatio;
-    node->setRect(QRectF(QPointF(0, 0), sizeInDips));
-    node->setOwnsTexture(true);
-    node->setTexture(delegate->createTextureFromImage(m_image));
+QImage DisplaySoftwareOutputSurface::Device::image()
+{
+    return m_image;
+}
 
-    return node;
+float DisplaySoftwareOutputSurface::Device::devicePixelRatio()
+{
+    return m_imageDevicePixelRatio;
 }
 
 DisplaySoftwareOutputSurface::DisplaySoftwareOutputSurface()
diff --git a/src/core/core_chromium.pri b/src/core/core_chromium.pri
index f2cedaf4a..14a65a39c 100644
--- a/src/core/core_chromium.pri
+++ b/src/core/core_chromium.pri
@@ -53,8 +53,8 @@ SOURCES = \
         common/qt_ipc_logging.cpp \
         common/qt_messages.cpp \
         common/user_script_data.cpp \
+        compositor/compositor.cpp \
         compositor/content_gpu_client_qt.cpp \
-        compositor/display_frame_sink.cpp \
         compositor/display_overrides.cpp \
         compositor/display_software_output_surface.cpp \
         content_client_qt.cpp \
@@ -157,8 +157,8 @@ HEADERS = \
         color_chooser_controller.h \
         common/qt_messages.h \
         common/user_script_data.h \
+        compositor/compositor.h \
         compositor/content_gpu_client_qt.h \
-        compositor/display_frame_sink.h \
         compositor/display_software_output_surface.h \
         content_client_qt.h \
         content_browser_client_qt.h \
@@ -293,8 +293,7 @@ qtConfig(webengine-printing-and-pdf) {
 contains(QT_CONFIG, opengl) {
     SOURCES += \
         compositor/compositor_resource_fence.cpp \
-        compositor/display_gl_output_surface.cpp \
-        compositor/display_gl_output_surface_qsg.cpp
+        compositor/display_gl_output_surface.cpp
     HEADERS += \
         compositor/compositor_resource_fence.h \
         compositor/display_gl_output_surface.h
diff --git a/src/core/render_widget_host_view_qt.cpp b/src/core/render_widget_host_view_qt.cpp
index 27229df81..9be6fac9a 100644
--- a/src/core/render_widget_host_view_qt.cpp
+++ b/src/core/render_widget_host_view_qt.cpp
@@ -148,9 +148,6 @@ RenderWidgetHostViewQt::RenderWidgetHostViewQt(content::RenderWidgetHost *widget
     m_uiCompositor->SetAcceleratedWidget(gfx::kNullAcceleratedWidget); // null means offscreen
     m_uiCompositor->SetRootLayer(m_rootLayer.get());
 
-    m_displayFrameSink = DisplayFrameSink::findOrCreate(m_uiCompositor->frame_sink_id());
-    m_displayFrameSink->connect(this);
-
     if (host()->delegate() && host()->delegate()->GetInputEventRouter())
         host()->delegate()->GetInputEventRouter()->AddFrameSinkIdOwner(GetFrameSinkId(), this);
 
@@ -172,8 +169,6 @@ RenderWidgetHostViewQt::~RenderWidgetHostViewQt()
 
     QObject::disconnect(m_adapterClientDestroyedConnection);
 
-    m_displayFrameSink->disconnect(this);
-
     if (text_input_manager_)
         text_input_manager_->RemoveObserver(this);
 
@@ -707,36 +702,12 @@ void RenderWidgetHostViewQt::OnDidUpdateVisualPropertiesComplete(const cc::Rende
 
 void RenderWidgetHostViewQt::OnDidFirstVisuallyNonEmptyPaint()
 {
-    if (m_loadVisuallyCommittedState == NotCommitted) {
-        m_loadVisuallyCommittedState = DidFirstVisuallyNonEmptyPaint;
-    } else if (m_loadVisuallyCommittedState == DidFirstCompositorFrameSwap) {
-        m_adapterClient->loadVisuallyCommitted();
-        m_loadVisuallyCommittedState = NotCommitted;
-    }
-}
-
-void RenderWidgetHostViewQt::scheduleUpdate()
-{
-    m_taskRunner->PostTask(
-            FROM_HERE,
-            base::BindOnce(&RenderWidgetHostViewQt::callUpdate, m_weakPtrFactory.GetWeakPtr()));
-}
-
-void RenderWidgetHostViewQt::callUpdate()
-{
-    m_delegate->update();
-
-    if (m_loadVisuallyCommittedState == NotCommitted) {
-        m_loadVisuallyCommittedState = DidFirstCompositorFrameSwap;
-    } else if (m_loadVisuallyCommittedState == DidFirstVisuallyNonEmptyPaint) {
-        m_adapterClient->loadVisuallyCommitted();
-        m_loadVisuallyCommittedState = NotCommitted;
-    }
+    m_adapterClient->didFirstVisuallyNonEmptyPaint();
 }
 
-QSGNode *RenderWidgetHostViewQt::updatePaintNode(QSGNode *oldNode)
+Compositor::Id RenderWidgetHostViewQt::compositorId()
 {
-    return m_displayFrameSink->updatePaintNode(oldNode, m_delegate.get());
+    return m_uiCompositor->frame_sink_id();
 }
 
 void RenderWidgetHostViewQt::notifyShown()
diff --git a/src/core/render_widget_host_view_qt.h b/src/core/render_widget_host_view_qt.h
index 42c44b007..7ed01f424 100644
--- a/src/core/render_widget_host_view_qt.h
+++ b/src/core/render_widget_host_view_qt.h
@@ -40,7 +40,7 @@
 #ifndef RENDER_WIDGET_HOST_VIEW_QT_H
 #define RENDER_WIDGET_HOST_VIEW_QT_H
 
-#include "compositor/display_frame_sink.h"
+#include "compositor/compositor.h"
 #include "delegated_frame_host_client_qt.h"
 #include "render_widget_host_view_qt_delegate.h"
 
@@ -81,15 +81,8 @@ class RenderWidgetHostViewQt
     , public ui::GestureProviderClient
     , public base::SupportsWeakPtr<RenderWidgetHostViewQt>
     , public content::TextInputManager::Observer
-    , public DisplayConsumer
 {
 public:
-    enum LoadVisuallyCommittedState {
-        NotCommitted,
-        DidFirstVisuallyNonEmptyPaint,
-        DidFirstCompositorFrameSwap
-    };
-
     RenderWidgetHostViewQt(content::RenderWidgetHost* widget);
     ~RenderWidgetHostViewQt();
 
@@ -172,11 +165,8 @@ public:
     // Overridden from content::RenderFrameMetadataProvider::Observer
     void OnRenderFrameMetadataChangedAfterActivation() override;
 
-    // Overridden from DisplayConsumer
-    void scheduleUpdate() override;
-
     // Called from RenderWidgetHostViewQtDelegateClient.
-    QSGNode *updatePaintNode(QSGNode *);
+    Compositor::Id compositorId();
     void notifyShown();
     void notifyHidden();
     bool updateScreenInfo();
@@ -205,7 +195,6 @@ private:
 
     bool isPopup() const;
     content::RenderFrameHost *getFocusedFrameHost();
-    void callUpdate();
 
     scoped_refptr<base::SingleThreadTaskRunner> m_taskRunner;
     ui::FilteredGestureProvider m_gestureProvider;
@@ -221,14 +210,12 @@ private:
     gfx::Vector2dF m_lastScrollOffset;
     gfx::SizeF m_lastContentsSize;
     DelegatedFrameHostClientQt m_delegatedFrameHostClient { this };
-    LoadVisuallyCommittedState m_loadVisuallyCommittedState = NotCommitted;
 
     // VIZ
     content::ScreenInfo m_screenInfo;
     std::unique_ptr<content::DelegatedFrameHost> m_delegatedFrameHost;
     std::unique_ptr<ui::Layer> m_rootLayer;
     std::unique_ptr<ui::Compositor> m_uiCompositor;
-    scoped_refptr<DisplayFrameSink> m_displayFrameSink;
     viz::ParentLocalSurfaceIdAllocator m_dfhLocalSurfaceIdAllocator;
     viz::ParentLocalSurfaceIdAllocator m_uiCompositorLocalSurfaceIdAllocator;
 
diff --git a/src/core/render_widget_host_view_qt_delegate.h b/src/core/render_widget_host_view_qt_delegate.h
index 0afe258f1..f5227bd52 100644
--- a/src/core/render_widget_host_view_qt_delegate.h
+++ b/src/core/render_widget_host_view_qt_delegate.h
@@ -59,13 +59,8 @@
 #include <QtGui/QImage>
 
 QT_BEGIN_NAMESPACE
-class QSGImageNode;
-class QSGLayer;
-class QSGRectangleNode;
-class QSGTexture;
 class QWheelEvent;
 class QWindow;
-
 QT_END_NAMESPACE
 
 namespace QtWebEngineCore {
@@ -84,11 +79,6 @@ public:
     virtual void hide() = 0;
     virtual bool isVisible() const = 0;
     virtual QWindow* window() const = 0;
-    virtual QSGTexture *createTextureFromImage(const QImage &) = 0;
-    virtual QSGLayer *createLayer() = 0;
-    virtual QSGImageNode *createImageNode() = 0;
-    virtual QSGRectangleNode *createRectangleNode() = 0;
-    virtual void update() = 0;
     virtual void updateCursor(const QCursor &) = 0;
     virtual void resize(int width, int height) = 0;
     virtual void move(const QPoint &) = 0;
diff --git a/src/core/render_widget_host_view_qt_delegate_client.cpp b/src/core/render_widget_host_view_qt_delegate_client.cpp
index d7674fd13..bee4bc4c2 100644
--- a/src/core/render_widget_host_view_qt_delegate_client.cpp
+++ b/src/core/render_widget_host_view_qt_delegate_client.cpp
@@ -204,9 +204,9 @@ RenderWidgetHostViewQtDelegateClient::RenderWidgetHostViewQtDelegateClient(
             context && context->hasCapability(QPlatformInputContext::HiddenTextCapability);
 }
 
-QSGNode *RenderWidgetHostViewQtDelegateClient::updatePaintNode(QSGNode *oldNode)
+Compositor::Id RenderWidgetHostViewQtDelegateClient::compositorId()
 {
-    return m_rwhv->updatePaintNode(oldNode);
+    return m_rwhv->compositorId();
 }
 
 void RenderWidgetHostViewQtDelegateClient::notifyShown()
diff --git a/src/core/render_widget_host_view_qt_delegate_client.h b/src/core/render_widget_host_view_qt_delegate_client.h
index bb14fe951..f67bed861 100644
--- a/src/core/render_widget_host_view_qt_delegate_client.h
+++ b/src/core/render_widget_host_view_qt_delegate_client.h
@@ -51,14 +51,13 @@
 #ifndef RENDER_WIDGET_HOST_VIEW_QT_DELEGATE_CLIENT_H
 #define RENDER_WIDGET_HOST_VIEW_QT_DELEGATE_CLIENT_H
 
-#include "qtwebenginecoreglobal_p.h"
+#include "compositor/compositor.h"
 
 #include <QtGui/QCursor>
 #include <QtGui/QTouchEvent>
 
 QT_BEGIN_NAMESPACE
 class QEvent;
-class QSGNode;
 class QVariant;
 
 class QMouseEvent;
@@ -88,7 +87,7 @@ class Q_WEBENGINECORE_PRIVATE_EXPORT RenderWidgetHostViewQtDelegateClient
 public:
     RenderWidgetHostViewQtDelegateClient(RenderWidgetHostViewQt *rwhv);
 
-    QSGNode *updatePaintNode(QSGNode *);
+    Compositor::Id compositorId();
     void notifyShown();
     void notifyHidden();
     void visualPropertiesChanged();
diff --git a/src/core/web_contents_adapter_client.h b/src/core/web_contents_adapter_client.h
index 04df99f0e..78040cc8d 100644
--- a/src/core/web_contents_adapter_client.h
+++ b/src/core/web_contents_adapter_client.h
@@ -465,7 +465,7 @@ public:
     virtual QColor backgroundColor() const = 0;
     virtual void loadStarted(const QUrl &provisionalUrl, bool isErrorPage = false) = 0;
     virtual void loadCommitted() = 0;
-    virtual void loadVisuallyCommitted() = 0;
+    virtual void didFirstVisuallyNonEmptyPaint() = 0;
     virtual void loadFinished(bool success, const QUrl &url, bool isErrorPage = false, int errorCode = 0, const QString &errorDescription = QString()) = 0;
     virtual void focusContainer() = 0;
     virtual void unhandledKeyEvent(QKeyEvent *event) = 0;