Update from https://crrev.com/306655

cc/resources/display_item_list.cc

+// Copyright 2014 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/resources/display_item_list.h"
+
+#include "base/debug/trace_event.h"
+#include "base/debug/trace_event_argument.h"
+#include "third_party/skia/include/core/SkCanvas.h"
+
+namespace cc {
+
+DisplayItemList::DisplayItemList()
+    : is_suitable_for_gpu_rasterization_(true), approximate_op_count_(0) {
+}
+
+scoped_refptr<DisplayItemList> DisplayItemList::Create() {
+  return make_scoped_refptr(new DisplayItemList());
+}
+
+DisplayItemList::~DisplayItemList() {
+}
+
+void DisplayItemList::Raster(SkCanvas* canvas,
+                             SkDrawPictureCallback* callback,
+                             float contents_scale) const {
+  canvas->save();
+  canvas->scale(contents_scale, contents_scale);
+  for (size_t i = 0; i < items_.size(); ++i) {
+    items_[i]->Raster(canvas, callback);
+  }
+  canvas->restore();
+}
+
+void DisplayItemList::AppendItem(scoped_ptr<DisplayItem> item) {
+  is_suitable_for_gpu_rasterization_ &= item->IsSuitableForGpuRasterization();
+  approximate_op_count_ += item->ApproximateOpCount();
+  items_.push_back(item.Pass());
+}
+
+bool DisplayItemList::IsSuitableForGpuRasterization() const {
+  // This is more permissive than Picture's implementation, since none of the
+  // items might individually trigger a veto even though they collectively have
+  // enough "bad" operations that a corresponding Picture would get vetoed.
+  return is_suitable_for_gpu_rasterization_;
+}
+
+int DisplayItemList::ApproximateOpCount() const {
+  return approximate_op_count_;
+}
+
+size_t DisplayItemList::PictureMemoryUsage() const {
+  size_t total_size = 0;
+
+  for (const auto& item : items_) {
+    total_size += item->PictureMemoryUsage();
+  }
+
+  return total_size;
+}
+
+scoped_refptr<base::debug::ConvertableToTraceFormat> DisplayItemList::AsValue()
+    const {
+  scoped_refptr<base::debug::TracedValue> state =
+      new base::debug::TracedValue();
+
+  // TODO(ajuma): Include the value of each item.
+  state->SetInteger("length", items_.size());
+  return state;
+}
+
+void DisplayItemList::EmitTraceSnapshot() const {
+  TRACE_EVENT_OBJECT_SNAPSHOT_WITH_ID(
+      TRACE_DISABLED_BY_DEFAULT("cc.debug") "," TRACE_DISABLED_BY_DEFAULT(
+          "devtools.timeline.picture"),
+      "cc::DisplayItemList", this, AsValue());
+}
+
+}  // namespace cc