CompositingReasonFinder should use a virtual function instead of a nest of branches

Source/core/rendering/RenderHTMLCanvas.cpp

Index: Source/core/rendering/RenderHTMLCanvas.cpp
diff --git a/Source/core/rendering/RenderHTMLCanvas.cpp b/Source/core/rendering/RenderHTMLCanvas.cpp
index 8e5ad0b1837533a16a10d59f078103ca216102a7..0b73b024bee5b1c5e6f7d887c3dcc9b5a31a8844 100644
--- a/Source/core/rendering/RenderHTMLCanvas.cpp
+++ b/Source/core/rendering/RenderHTMLCanvas.cpp
@@ -111,4 +111,16 @@ void RenderHTMLCanvas::canvasSizeChanged()
         setNeedsLayout();
 }
 
+CompositingReasons RenderHTMLCanvas::additionalCompositingReasons(CompositingTriggerFlags triggers) const
+{
+    if (!(triggers & CanvasTrigger))
+        return CompositingReasonNone;
+
+    HTMLCanvasElement* canvas = toHTMLCanvasElement(node());
+    if (canvas->renderingContext() && canvas->renderingContext()->isAccelerated())
+        return CompositingReasonCanvas;
+
+    return CompositingReasonNone;
+}
+
 } // namespace WebCore