cc: Devirtualize DisplayItem::ExternalMemoryUsage().

cc/playback/transform_display_item.cc

Index: cc/playback/transform_display_item.cc
diff --git a/cc/playback/transform_display_item.cc b/cc/playback/transform_display_item.cc
index ef281362674939de39e864c6283fb019a7240146..a495d9a82f4dbcf6dc28d816a9e2316895e3cbda 100644
--- a/cc/playback/transform_display_item.cc
+++ b/cc/playback/transform_display_item.cc
@@ -15,11 +15,12 @@
 namespace cc {
 
 TransformDisplayItem::TransformDisplayItem(const gfx::Transform& transform)
-    : transform_(gfx::Transform::kSkipInitialization) {
+    : DisplayItem(TRANSFORM), transform_(gfx::Transform::kSkipInitialization) {
   SetNew(transform);
 }
 
-TransformDisplayItem::TransformDisplayItem(const proto::DisplayItem& proto) {
+TransformDisplayItem::TransformDisplayItem(const proto::DisplayItem& proto)
+    : DisplayItem(TRANSFORM) {
   DCHECK_EQ(proto::DisplayItem::Type_Transform, proto.type());
 
   const proto::TransformDisplayItem& details = proto.transform_item();
@@ -57,14 +58,12 @@ void TransformDisplayItem::AsValueInto(
       transform_.ToString().c_str(), visual_rect.ToString().c_str()));
 }
 
-size_t TransformDisplayItem::ExternalMemoryUsage() const {
-  return 0;
-}
-
-EndTransformDisplayItem::EndTransformDisplayItem() {}
+EndTransformDisplayItem::EndTransformDisplayItem()
+    : DisplayItem(END_TRANSFORM) {}
 
 EndTransformDisplayItem::EndTransformDisplayItem(
-    const proto::DisplayItem& proto) {
+    const proto::DisplayItem& proto)
+    : DisplayItem(END_TRANSFORM) {
   DCHECK_EQ(proto::DisplayItem::Type_EndTransform, proto.type());
 }
 
@@ -89,8 +88,4 @@ void EndTransformDisplayItem::AsValueInto(
                          visual_rect.ToString().c_str()));
 }
 
-size_t EndTransformDisplayItem::ExternalMemoryUsage() const {
-  return 0;
-}
-
 }  // namespace cc