Add DisplayItemListPictureRecorder

Source/platform/graphics/paint/DisplayItemListPictureRecorder.h

+// 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.
+
+#ifndef DisplayItemListPictureRecorder_h
+#define DisplayItemListPictureRecorder_h
+
+#include "platform/RuntimeEnabledFeatures.h"
+#include "platform/graphics/GraphicsContext.h"
+#include "platform/graphics/paint/DisplayItemList.h"
+#include "wtf/OwnPtr.h"
+
+namespace blink {
+
+class DisplayItemListPictureRecorder {
+    WTF_MAKE_NONCOPYABLE(DisplayItemListPictureRecorder);
+    STACK_ALLOCATED();
+public:
+    DisplayItemListPictureRecorder(const FloatRect& bounds)
+        : m_displayItemList(RuntimeEnabledFeatures::slimmingPaintEnabled() ? DisplayItemList::create() : nullptr)
+        , m_context(nullptr, m_displayItemList.get())
+#if ENABLE(ASSERT)
+        , m_recordingEnded(false)
+#endif
+    {
+        m_context.beginRecording(bounds);
+    }
+
+    ~DisplayItemListPictureRecorder()
+    {
+        ASSERT(m_recordingEnded);
+    }
+
+    GraphicsContext& context() { return m_context; }
+
+    PassRefPtr<const SkPicture> endRecording()
+    {
+#if ENABLE(ASSERT)
+        ASSERT(!m_recordingEnded);
+        m_recordingEnded = true;
+#endif
+
+        if (m_displayItemList)
+            m_displayItemList->replay(&m_context);
+
+        return m_context.endRecording();
+    }
+
+private:
+    OwnPtr<DisplayItemList> m_displayItemList;
+    GraphicsContext m_context;
+
+#if ENABLE(ASSERT)
+    bool m_recordingEnded;
+#endif
+};
+
+} // namespace blink
+
+#endif // DisplayItemListPictureRecorder_h