cc: Devirtualize DisplayItem::ExternalMemoryUsage().

cc/playback/display_item.h

 // 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.
 
 #ifndef CC_PLAYBACK_DISPLAY_ITEM_H_
 #define CC_PLAYBACK_DISPLAY_ITEM_H_
 
 #include <stddef.h>
 
 #include <memory>
 
 #include "cc/base/cc_export.h"
 #include "cc/debug/traced_value.h"
 #include "third_party/skia/include/core/SkPicture.h"
 #include "ui/gfx/geometry/rect.h"
 
 class SkCanvas;
 
 namespace cc {
 
 namespace proto {
 class DisplayItem;
 }  // namespace proto
 
 class CC_EXPORT DisplayItem {
  public:
+  enum Type {
+    CLIP,
+    END_CLIP,
+    CLIP_PATH,
+    END_CLIP_PATH,
+    COMPOSITING,
+    END_COMPOSITING,
+    DRAWING,
+    FILTER,
+    END_FILTER,
+    FLOAT_CLIP,
+    END_FLOAT_CLIP,
+    TRANSFORM,
+    END_TRANSFORM,
+  };
+
   virtual ~DisplayItem() {}
 
   virtual void ToProtobuf(proto::DisplayItem* proto) const = 0;
   virtual sk_sp<const SkPicture> GetPicture() const;
   virtual void Raster(SkCanvas* canvas,
                       SkPicture::AbortCallback* callback) const = 0;
   virtual void AsValueInto(const gfx::Rect& visual_rect,
                            base::trace_event::TracedValue* array) const = 0;
-  // For tracing.
-  virtual size_t ExternalMemoryUsage() const = 0;
+
+  Type type() const { return type_; }
 
  protected:
-  DisplayItem();
+  explicit DisplayItem(Type type) : type_(type) {}
+
+  const Type type_;
 };
 
 }  // namespace cc
 
 #endif  // CC_PLAYBACK_DISPLAY_ITEM_H_