cc: Remove AsValue virtual from DisplayItem.

cc/debug/traced_display_item_list.cc

-// 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 "cc/debug/traced_display_item_list.h"
-
-#include "base/json/json_writer.h"
-#include "cc/debug/traced_value.h"
-#include "cc/playback/display_item_list.h"
-
-namespace cc {
-
-TracedDisplayItemList::TracedDisplayItemList(
-    scoped_refptr<const DisplayItemList> list,
-    bool include_items)
-    : display_item_list_(list), include_items_(include_items) {
-}
-
-TracedDisplayItemList::~TracedDisplayItemList() {
-}
-
-void TracedDisplayItemList::AppendAsTraceFormat(std::string* out) const {
-  std::unique_ptr<base::trace_event::ConvertableToTraceFormat> convertable(
-      display_item_list_->AsValue(include_items_));
-  convertable->AppendAsTraceFormat(out);
-}
-
-}  // namespace cc