NOCOMMIT: Blink tracing now uses base

third_party/WebKit/Source/core/layout/TracedLayoutObject.h

Index: third_party/WebKit/Source/core/layout/TracedLayoutObject.h
diff --git a/third_party/WebKit/Source/core/layout/TracedLayoutObject.h b/third_party/WebKit/Source/core/layout/TracedLayoutObject.h
index 079dc728fe90a8da3e3b9038e651c22046cb35d8..f40d194cd91d5c1afa09efb620a0954bb89cbebf 100644
--- a/third_party/WebKit/Source/core/layout/TracedLayoutObject.h
+++ b/third_party/WebKit/Source/core/layout/TracedLayoutObject.h
@@ -5,8 +5,10 @@
 #ifndef TracedLayoutObject_h
 #define TracedLayoutObject_h
 
+#include "base/trace_event/trace_event.h"
 #include "platform/EventTracer.h"
 #include "platform/geometry/LayoutRect.h"
+#include "wtf/text/WTFString.h"
 #include "wtf/Vector.h"
 
 namespace blink {
@@ -15,12 +17,12 @@ class JSONObject;
 class LayoutObject;
 class LayoutView;
 
-class TracedLayoutObject : public TraceEvent::ConvertableToTraceFormat {
+class TracedLayoutObject : public base::trace_event::ConvertableToTraceFormat {
     WTF_MAKE_NONCOPYABLE(TracedLayoutObject);
 public:
-    static PassRefPtr<TraceEvent::ConvertableToTraceFormat> create(const LayoutView&, bool traceGeometry = true);
+    static scoped_refptr<base::trace_event::ConvertableToTraceFormat> create(const LayoutView&, bool traceGeometry = true);
 
-    String asTraceFormat() const override;
+    void AppendAsTraceFormat(std::string* out) const override;
 
 private:
     explicit TracedLayoutObject(const LayoutObject&, bool traceGeometry);
@@ -48,7 +50,7 @@ private:
     unsigned m_col;
     unsigned m_rowSpan;
     unsigned m_colSpan;
-    Vector<RefPtr<TracedLayoutObject>> m_children;
+    Vector<scoped_refptr<TracedLayoutObject>> m_children;
 };
 
 } // namespace blink