First step of PaintInvalidator implementation

third_party/WebKit/Source/core/paint/HTMLCanvasPaintInvalidator.cpp

+// Copyright 2016 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 "core/paint/HTMLCanvasPaintInvalidator.h"
+
+#include "core/html/HTMLCanvasElement.h"
+#include "core/layout/LayoutHTMLCanvas.h"
+#include "core/paint/BoxPaintInvalidator.h"
+#include "core/paint/PaintInvalidator.h"
+
+namespace blink {
+
+PaintInvalidationReason HTMLCanvasPaintInvalidator::invalidatePaintIfNeeded()
+{
+    PaintInvalidationReason reason = BoxPaintInvalidator(m_htmlCanvas, m_context).invalidatePaintIfNeeded();
+
+    HTMLCanvasElement* element = toHTMLCanvasElement(m_htmlCanvas.node());
+    if (element->isDirty()) {
+        element->doDeferredPaintInvalidation();
+        if (reason < PaintInvalidationRectangle)
+            reason = PaintInvalidationRectangle;
+    }
+
+    return reason;
+}
+
+} // namespace blink