10 files changed, 504 insertions, 530 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()