New display item caching

Source/platform/graphics/paint/CachedDisplayItem.cpp

Index: Source/platform/graphics/paint/CachedDisplayItem.cpp
diff --git a/Source/platform/graphics/paint/CachedDisplayItem.cpp b/Source/platform/graphics/paint/CachedDisplayItem.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..3b4e1361eceb3a27036bcfed71d2ee6861f84025
--- /dev/null
+++ b/Source/platform/graphics/paint/CachedDisplayItem.cpp
@@ -0,0 +1,39 @@
+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "config.h"
+#include "platform/graphics/paint/CachedDisplayItem.h"
+
+#include "platform/graphics/GraphicsContext.h"
+#include "public/platform/WebDisplayItemList.h"
+#include "third_party/skia/include/core/SkPicture.h"
+
+namespace blink {
+
+#ifndef NDEBUG
+
+static void drawRedRect(GraphicsContext& context, const FloatRect& bounds)
+{
+    SkPaint paint;
+    paint.setColor(SK_ColorRED);

[Stephen Chennney, 2015/01/27 19:45:45]

bikeshed: Red is probably OK, but better is something even more obnoxious and
not likely to be seen on a page. Purple might be better because it is very rare
in web content and stands out visually.

[trchen, 2015/01/27 19:52:01]

I would vote for red for the sake of consistency, since it is already used in
GraphicsLayer and FramePainter for debugging.

+    context.drawRect(bounds, paint);
+}
+
+void CachedDisplayItem::replay(GraphicsContext* context)
+{
+    drawRedRect(*context, m_bounds);
+}
+
+void CachedDisplayItem::appendToWebDisplayItemList(WebDisplayItemList* list) const
+{
+    GraphicsContext context(nullptr, nullptr);
+    context.beginRecording(m_bounds);
+    drawRedRect(context, m_bounds);
+    RefPtr<const SkPicture> picture = context.endRecording();
+    list->appendDrawingItem(const_cast<SkPicture*>(picture.get()), FloatPoint());
+}
+
+#endif // ifndef NDEBUG
+
+} // namespace blink