Simplify the BackingStore handling.

This patch removes the black borders around the widget when resizing.

- No need to resize the BackingStore direcly, RenderWidgetHostImpl::WasResized
  takes care of allocating a new one with the correct size.
- Get the backing store just before painting instead of pushing it when
  scheduling an update. Getting the backing store has side effects that
  assumes it is done that way.
- Remove the about_to_validate_and_paint_ check as all our painting updates
  are scheduled back to the event loop and that we are now only fetching
  the BackingStore at this point.

9 files changed, 34 insertions, 103 deletions

diff --git a/lib/render_widget_host_view_qt_delegate_quick.cpp b/lib/render_widget_host_view_qt_delegate_quick.cpp
index 754e68239..13e4ef29f 100644
--- a/lib/render_widget_host_view_qt_delegate_quick.cpp
+++ b/lib/render_widget_host_view_qt_delegate_quick.cpp
@@ -2,6 +2,9 @@
 
 #include "shared/backing_store_qt.h"
 #include "shared/render_widget_host_view_qt.h"
+
+#include "content/browser/renderer_host/render_view_host_impl.h"
+
 #include <QQuickWindow>
 #include <QWindow>
 
@@ -42,6 +45,7 @@ QWindow* RenderWidgetHostViewQtDelegateQuick::window() const
 
 void RenderWidgetHostViewQtDelegateQuick::update(const QRect& rect)
 {
+    polish();
     QQuickPaintedItem::update(rect);
 }
 
@@ -53,29 +57,19 @@ void RenderWidgetHostViewQtDelegateQuick::paint(QPainter *painter)
     m_backingStore->paintToTarget(painter, boundingRect());
 }
 
-void RenderWidgetHostViewQtDelegateQuick::setBackingStore(BackingStoreQt* backingStore)
-{
-    m_backingStore = backingStore;
-    if (m_backingStore)
-        m_backingStore->resize(QSize(width(), height()));
-}
-
-QSGNode * RenderWidgetHostViewQtDelegateQuick::updatePaintNode(QSGNode * oldNode, UpdatePaintNodeData * data)
+void RenderWidgetHostViewQtDelegateQuick::updatePolish()
 {
-    return QQuickPaintedItem::updatePaintNode(oldNode, data);
+    // paint will be called from the scene graph thread and this doesn't play well
+    // with chromium's use of TLS while getting the backing store.
+    // updatePolish() should be called from the GUI thread right before the rendering thread starts.
+    m_backingStore = m_view->GetBackingStore();
 }
 
 void RenderWidgetHostViewQtDelegateQuick::geometryChanged(const QRectF &newGeometry, const QRectF &oldGeometry)
 {
     QQuickPaintedItem::geometryChanged(newGeometry, oldGeometry);
 
-    resizeBackingStore();
-}
-
-void RenderWidgetHostViewQtDelegateQuick::resizeBackingStore()
-{
-    if (m_backingStore)
-        m_backingStore->resize(QSize(width(), height()));
+    m_view->GetRenderWidgetHost()->WasResized();
 }
 
 void RenderWidgetHostViewQtDelegateQuick::focusInEvent(QFocusEvent *event)
diff --git a/lib/render_widget_host_view_qt_delegate_quick.h b/lib/render_widget_host_view_qt_delegate_quick.h
index 20725c621..20bd263f8 100644
--- a/lib/render_widget_host_view_qt_delegate_quick.h
+++ b/lib/render_widget_host_view_qt_delegate_quick.h
@@ -23,7 +23,6 @@ class RenderWidgetHostViewQtDelegateQuick : public QQuickPaintedItem, public Ren
 public:
     RenderWidgetHostViewQtDelegateQuick(content::RenderWidgetHostViewQt* view, QQuickItem *parent = 0);
 
-    virtual void setBackingStore(BackingStoreQt* backingStore);
     virtual QRectF screenRect() const;
     virtual void show();
     virtual void hide();
@@ -43,11 +42,8 @@ public:
     void keyReleaseEvent(QKeyEvent*);
     void wheelEvent(QWheelEvent*);
 
-protected Q_SLOTS:
-    void resizeBackingStore();
-
 protected:
-    QSGNode* updatePaintNode(QSGNode * oldNode, UpdatePaintNodeData * data);
+    void updatePolish();
     void geometryChanged(const QRectF &newGeometry, const QRectF &oldGeometry);
 
 private:
diff --git a/lib/render_widget_host_view_qt_delegate_widget.cpp b/lib/render_widget_host_view_qt_delegate_widget.cpp
index 8be1d308f..9a659069f 100644
--- a/lib/render_widget_host_view_qt_delegate_widget.cpp
+++ b/lib/render_widget_host_view_qt_delegate_widget.cpp
@@ -3,13 +3,14 @@
 #include "shared/backing_store_qt.h"
 #include "shared/render_widget_host_view_qt.h"
 
+#include "content/browser/renderer_host/render_view_host_impl.h"
+
 #include <QResizeEvent>
 #include <QPaintEvent>
 
 RenderWidgetHostViewQtDelegateWidget::RenderWidgetHostViewQtDelegateWidget(content::RenderWidgetHostViewQt* view, QWidget *parent)
     : QWidget(parent)
     , m_painter(0)
-    , m_backingStore(0)
     , m_view(view)
 {
     setFocusPolicy(Qt::ClickFocus);
@@ -47,19 +48,12 @@ void RenderWidgetHostViewQtDelegateWidget::update(const QRect& rect)
     QWidget::update(rect);
 }
 
-void RenderWidgetHostViewQtDelegateWidget::setBackingStore(BackingStoreQt* backingStore)
-{
-    m_backingStore = backingStore;
-    if (m_backingStore)
-        m_backingStore->resize(size());
-}
-
 void RenderWidgetHostViewQtDelegateWidget::paintEvent(QPaintEvent * event)
 {
-    if (!m_backingStore)
-        return;
-    QPainter painter(this);
-    m_backingStore->paintToTarget(&painter, event->rect());
+    if (BackingStoreQt *backingStore = m_view->GetBackingStore()) {
+        QPainter painter(this);
+        backingStore->paintToTarget(&painter, event->rect());
+    }
 }
 
 QPainter* RenderWidgetHostViewQtDelegateWidget::painter()
@@ -71,9 +65,7 @@ QPainter* RenderWidgetHostViewQtDelegateWidget::painter()
 
 void RenderWidgetHostViewQtDelegateWidget::resizeEvent(QResizeEvent *resizeEvent)
 {
-    if (m_backingStore)
-        m_backingStore->resize(resizeEvent->size());
-    QWidget::update();
+    m_view->GetRenderWidgetHost()->WasResized();
 }
 
 bool RenderWidgetHostViewQtDelegateWidget::event(QEvent *event)
diff --git a/lib/render_widget_host_view_qt_delegate_widget.h b/lib/render_widget_host_view_qt_delegate_widget.h
index 9087ba017..f6da4f484 100644
--- a/lib/render_widget_host_view_qt_delegate_widget.h
+++ b/lib/render_widget_host_view_qt_delegate_widget.h
@@ -17,7 +17,6 @@ class RenderWidgetHostViewQtDelegateWidget : public QWidget, public RenderWidget
 public:
     RenderWidgetHostViewQtDelegateWidget(content::RenderWidgetHostViewQt* view, QWidget *parent = 0);
 
-    virtual void setBackingStore(BackingStoreQt* backingStore);
     virtual QRectF screenRect() const;
     virtual void show();
     virtual void hide();
@@ -33,7 +32,6 @@ protected:
     void resizeEvent(QResizeEvent *resizeEvent);
 
 private:
-    BackingStoreQt* m_backingStore;
     QPainter* m_painter;
     content::RenderWidgetHostViewQt *m_view;
 };
diff --git a/shared/backing_store_qt.cpp b/shared/backing_store_qt.cpp
index 8920b72c3..cee0d093e 100644
--- a/shared/backing_store_qt.cpp
+++ b/shared/backing_store_qt.cpp
@@ -49,34 +49,15 @@
 #include <QPainter>
 
 BackingStoreQt::BackingStoreQt(content::RenderWidgetHost *host, const gfx::Size &size, QWindow* parent)
-    : m_host(content::RenderWidgetHostImpl::From(host))
+    : content::BackingStore(host, size)
     , m_pixelBuffer(size.width(), size.height())
-    , content::BackingStore(host, size)
-    , m_isValid(false)
 {
-    int width = size.width();
-    int height = size.height();
-    resize(QSize(width, height));
 }
 
 BackingStoreQt::~BackingStoreQt()
 {
 }
 
-void BackingStoreQt::resize(const QSize& size)
-{
-    m_isValid = false;
-    if (size != m_pixelBuffer.size()) {
-        QPixmap oldBackingStore = m_pixelBuffer;
-        m_pixelBuffer = QPixmap(size);
-
-        QPainter painter(&m_pixelBuffer);
-        painter.drawPixmap(oldBackingStore.rect(), oldBackingStore);
-
-        m_host->WasResized();
-    }
-}
-
 void BackingStoreQt::paintToTarget(QPainter* painter, const QRectF& rect)
 {
     if (m_pixelBuffer.isNull())
@@ -105,9 +86,9 @@ void BackingStoreQt::PaintToBackingStore(content::RenderProcessHost *process,
     uint8_t* bitmapData = static_cast<uint8_t*>(dib->memory());
     int width = m_pixelBuffer.size().width();
     int height = m_pixelBuffer.size().height();
-    QImage img(bitmapData, pixel_bitmap_rect.width(), pixel_bitmap_rect.height(), QImage::Format_ARGB32);
+    const QImage img(bitmapData, pixel_bitmap_rect.width(), pixel_bitmap_rect.height(), QImage::Format_ARGB32);
 
-    m_painter.begin(&m_pixelBuffer);
+    QPainter painter(&m_pixelBuffer);
 
     for (size_t i = 0; i < copy_rects.size(); ++i) {
         gfx::Rect copy_rect = gfx::ToEnclosedRect(gfx::ScaleRect(copy_rects[i], scale_factor));
@@ -122,10 +103,8 @@ void BackingStoreQt::PaintToBackingStore(content::RenderProcessHost *process,
                                  , copy_rect.width()
                                  , copy_rect.height());
 
-        m_painter.drawPixmap(destination, QPixmap::fromImage(img), source);
+        painter.drawImage(destination, img, source);
     }
-
-    m_painter.end();
 }
 
 void BackingStoreQt::ScrollBackingStore(const gfx::Vector2d &delta, const gfx::Rect &clip_rect, const gfx::Size &view_size)
diff --git a/shared/backing_store_qt.h b/shared/backing_store_qt.h
index 9f7e807d3..d2fa52f38 100644
--- a/shared/backing_store_qt.h
+++ b/shared/backing_store_qt.h
@@ -53,7 +53,6 @@ public:
     BackingStoreQt(content::RenderWidgetHost *host, const gfx::Size &size, QWindow* parent);
     ~BackingStoreQt();
 
-    void resize(const QSize& size);
     void paintToTarget(QPainter*, const QRectF& rect);
 
     virtual void PaintToBackingStore(content::RenderProcessHost *process, TransportDIB::Id bitmap, const gfx::Rect &bitmap_rect,
@@ -64,10 +63,7 @@ public:
     virtual bool CopyFromBackingStore(const gfx::Rect &rect, skia::PlatformBitmap *output);
 
 private:
-    QPainter m_painter;
-    content::RenderWidgetHost* m_host;
     QPixmap m_pixelBuffer;
-    bool m_isValid;
 };
 
 #endif
diff --git a/shared/render_widget_host_view_qt.cpp b/shared/render_widget_host_view_qt.cpp
index 759667000..305a4f6b8 100644
--- a/shared/render_widget_host_view_qt.cpp
+++ b/shared/render_widget_host_view_qt.cpp
@@ -90,7 +90,6 @@ void RenderWidgetHostViewPort::GetDefaultScreenInfo(WebKit::WebScreenInfo* resul
 RenderWidgetHostViewQt::RenderWidgetHostViewQt(content::RenderWidgetHost* widget)
     : m_host(content::RenderWidgetHostImpl::From(widget))
     , m_delegate(0)
-    , about_to_validate_and_paint_(false)
 {
     m_host->SetView(this);
 }
@@ -125,6 +124,12 @@ bool RenderWidgetHostViewQt::handleEvent(QEvent* event) {
     return true;
 }
 
+BackingStoreQt* RenderWidgetHostViewQt::GetBackingStore()
+{
+    bool force_create = !m_host->empty();
+    return static_cast<BackingStoreQt*>(m_host->GetBackingStore(force_create));
+}
+
 content::BackingStore *RenderWidgetHostViewQt::AllocBackingStore(const gfx::Size &size)
 {
     return new BackingStoreQt(m_host, size, new QWindow);
@@ -327,20 +332,13 @@ void RenderWidgetHostViewQt::DidUpdateBackingStore(const gfx::Rect& scroll_rect,
     if (!m_delegate->isVisible())
         return;
 
-    if (about_to_validate_and_paint_)
-        invalid_rect_.Union(scroll_rect);
-    else
-        Paint(scroll_rect);
+    Paint(scroll_rect);
 
     for (size_t i = 0; i < copy_rects.size(); ++i) {
         gfx::Rect rect = gfx::SubtractRects(copy_rects[i], scroll_rect);
         if (rect.IsEmpty())
             continue;
-
-        if (about_to_validate_and_paint_)
-            invalid_rect_.Union(rect);
-        else
-            Paint(rect);
+        Paint(rect);
     }
 }
 
@@ -458,22 +456,8 @@ void RenderWidgetHostViewQt::OnAccessibilityNotifications(const std::vector<Acce
 
 void RenderWidgetHostViewQt::Paint(const gfx::Rect& damage_rect)
 {
-    DCHECK(!about_to_validate_and_paint_);
-
-    invalid_rect_ = damage_rect;
-    about_to_validate_and_paint_ = true;
-
-    bool force_create = !m_host->empty();
-    BackingStoreQt* backing_store = static_cast<BackingStoreQt*>(m_host->GetBackingStore(force_create));
-
-    // Calling GetBackingStore maybe have changed |invalid_rect_|...
-    about_to_validate_and_paint_ = false;
-
-    if (backing_store) {
-        m_delegate->setBackingStore(backing_store);
-        QRect r(invalid_rect_.x(), invalid_rect_.y(), invalid_rect_.width(), invalid_rect_.height());
-        m_delegate->update(r);
-    }
+    QRect r(damage_rect.x(), damage_rect.y(), damage_rect.width(), damage_rect.height());
+    m_delegate->update(r);
 }
 
 bool RenderWidgetHostViewQt::IsPopup() const
diff --git a/shared/render_widget_host_view_qt.h b/shared/render_widget_host_view_qt.h
index 79b9921ae..9ff200c32 100644
--- a/shared/render_widget_host_view_qt.h
+++ b/shared/render_widget_host_view_qt.h
@@ -51,6 +51,7 @@
 #define QT_NOT_YET_IMPLEMENTED qt_noop();
 #endif
 
+class BackingStoreQt;
 class QEvent;
 class QFocusEvent;
 class QKeyEvent;
@@ -69,6 +70,7 @@ public:
 
     void SetDelegate(RenderWidgetHostViewQtDelegate* delegate) { m_delegate = delegate; }
     bool handleEvent(QEvent* event);
+    BackingStoreQt* GetBackingStore();
 
     virtual content::BackingStore *AllocBackingStore(const gfx::Size &size);
 
@@ -139,14 +141,6 @@ private:
     content::RenderWidgetHostImpl *m_host;
     RenderWidgetHostViewQtDelegate *m_delegate;
     gfx::Size m_requestedSize;
-
-    // This is true when we are currently painting and thus should handle extra
-    // paint requests by expanding the invalid rect rather than actually
-    // painting.
-    bool about_to_validate_and_paint_;
-
-    // This is the rectangle which we'll paint.
-    gfx::Rect invalid_rect_;
 };
 
 }
diff --git a/shared/render_widget_host_view_qt_delegate.h b/shared/render_widget_host_view_qt_delegate.h
index c01d7d942..7f147dae6 100644
--- a/shared/render_widget_host_view_qt_delegate.h
+++ b/shared/render_widget_host_view_qt_delegate.h
@@ -3,13 +3,11 @@
 
 #include <QRect>
 
-class BackingStoreQt;
 class QWindow;
 
 class RenderWidgetHostViewQtDelegate {
 public:
     virtual ~RenderWidgetHostViewQtDelegate() {}
-    virtual void setBackingStore(BackingStoreQt* backingStore) = 0;
     virtual QRectF screenRect() const = 0;
     virtual void show() = 0;
     virtual void hide() = 0;