[Slimming Paint] Paint the inspector overlay with GraphicsLayer DisplayList.

Source/web/PageOverlay.cpp

Index: Source/web/PageOverlay.cpp
diff --git a/Source/web/PageOverlay.cpp b/Source/web/PageOverlay.cpp
index b909ca64831626737a3ef8b5ec45ce803d7625af..4bf3c8286c1dd3b3d39b460789727b225ffd9803 100644
--- a/Source/web/PageOverlay.cpp
+++ b/Source/web/PageOverlay.cpp
@@ -32,8 +32,10 @@
 #include "core/frame/Settings.h"
 #include "core/page/Page.h"
 #include "platform/graphics/GraphicsContext.h"
+#include "platform/graphics/GraphicsContextStateSaver.h"
 #include "platform/graphics/GraphicsLayer.h"
-#include "platform/graphics/GraphicsLayerClient.h"
+#include "platform/graphics/paint/DisplayItem.h"
+#include "platform/graphics/paint/DrawingRecorder.h"
 #include "public/platform/WebLayer.h"
 #include "public/web/WebPageOverlay.h"
 #include "public/web/WebViewClient.h"
@@ -41,56 +43,31 @@
 
 namespace blink {
 
-namespace {
-
-WebCanvas* ToWebCanvas(GraphicsContext* gc)
+PassOwnPtr<PageOverlay> PageOverlay::create(WebViewImpl* viewImpl, WebPageOverlay* overlay)
 {
-    return gc->canvas();
+    return adoptPtr(new PageOverlay(viewImpl, overlay));
 }
 
-} // namespace
-
-PassOwnPtr<PageOverlay> PageOverlay::create(WebViewImpl* viewImpl, WebPageOverlay* overlay)
+PassOwnPtr<PageOverlay> PageOverlay::create(WebViewImpl* viewImpl, PageOverlay::Painter* overlayPainter)
 {
-    return adoptPtr(new PageOverlay(viewImpl, overlay));
+    return adoptPtr(new PageOverlay(viewImpl, overlayPainter));
 }
 
 PageOverlay::PageOverlay(WebViewImpl* viewImpl, WebPageOverlay* overlay)
     : m_viewImpl(viewImpl)
     , m_overlay(overlay)
+    , m_overlayPainter(nullptr)
     , m_zOrder(0)
 {
 }
 
-class OverlayGraphicsLayerClientImpl : public GraphicsLayerClient {
-public:
-    static PassOwnPtr<OverlayGraphicsLayerClientImpl> create(WebPageOverlay* overlay)
-    {
-        return adoptPtr(new OverlayGraphicsLayerClientImpl(overlay));
-    }
-
-    virtual ~OverlayGraphicsLayerClientImpl() { }
-
-    virtual void paintContents(const GraphicsLayer*, GraphicsContext& gc, GraphicsLayerPaintingPhase, const IntRect& inClip)
-    {
-        gc.save();
-        m_overlay->paintPageOverlay(ToWebCanvas(&gc));
-        gc.restore();
-    }
-
-    virtual String debugName(const GraphicsLayer* graphicsLayer) override
-    {
-        return String("WebViewImpl Page Overlay Content Layer");
-    }
-
-private:
-    explicit OverlayGraphicsLayerClientImpl(WebPageOverlay* overlay)
-        : m_overlay(overlay)
-    {
-    }
-
-    WebPageOverlay* m_overlay;
-};
+PageOverlay::PageOverlay(WebViewImpl* viewImpl, PageOverlay::Painter* overlayPainter)
+    : m_viewImpl(viewImpl)
+    , m_overlay(nullptr)
+    , m_overlayPainter(overlayPainter)
+    , m_zOrder(0)
+{
+}
 
 void PageOverlay::clear()
 {
@@ -101,7 +78,6 @@ void PageOverlay::clear()
         if (Page* page = m_viewImpl->page())
             page->inspectorController().didRemovePageOverlay(m_layer.get());
         m_layer = nullptr;
-        m_layerClient = nullptr;
     }
 }
 
@@ -110,8 +86,7 @@ void PageOverlay::update()
     invalidateWebFrame();
 
     if (!m_layer) {
-        m_layerClient = OverlayGraphicsLayerClientImpl::create(m_overlay);
-        m_layer = GraphicsLayer::create(m_viewImpl->graphicsLayerFactory(), m_layerClient.get());
+        m_layer = GraphicsLayer::create(m_viewImpl->graphicsLayerFactory(), this /* client */);
         m_layer->setDrawsContent(true);
 
         if (Page* page = m_viewImpl->page())
@@ -136,13 +111,33 @@ void PageOverlay::update()
 
 void PageOverlay::paintWebFrame(GraphicsContext& gc)
 {
-    if (!m_viewImpl->isAcceleratedCompositingActive()) {
-        gc.save();
-        m_overlay->paintPageOverlay(ToWebCanvas(&gc));
-        gc.restore();
+    if (m_overlay) {
+        // We clip the painted contents to the WebViewImpl, because
+        // DrawingRecorder expects to know bounds.
+        DisplayItemClient displayItemClient = static_cast<DisplayItemClient>(static_cast<void*>(this));
+        IntSize size = m_viewImpl->size();
+        FloatRect clipRect(FloatPoint(0, 0), size);
+        DrawingRecorder recorder(&gc, displayItemClient, DisplayItem::PageOverlay, clipRect);
+        GraphicsContextStateSaver saver(gc);
+        gc.clipRect(clipRect);
+        m_overlay->paintPageOverlay(gc.canvas());
+    } else if (m_overlayPainter) {
+        // FIXME: Maybe we need to make the callee responsible for saving.
+        // We can't save a GraphicsContext unless we have a canvas.
+        m_overlayPainter->paintPageOverlay(gc);
     }
 }
 
+void PageOverlay::paintContents(const GraphicsLayer*, GraphicsContext& gc, GraphicsLayerPaintingPhase, const IntRect& inClip)
+{
+    paintWebFrame(gc);
+}
+
+String PageOverlay::debugName(const GraphicsLayer*)
+{
+    return "WebViewImpl Page Overlay Content Layer";
+}
+
 void PageOverlay::invalidateWebFrame()
 {
     // WebPageOverlay does the actual painting of the overlay.