cc: Use a ListContainer for DisplayItemList to reduce allocations.

ui/compositor/clip_transform_recorder.h

Index: ui/compositor/clip_transform_recorder.h
diff --git a/ui/compositor/clip_transform_recorder.h b/ui/compositor/clip_transform_recorder.h
index 7ca70f3de3c16fad59bf7ac2971e64a05809f1ad..84f340d75ac318475c173b5f2581f329b30578bf 100644
--- a/ui/compositor/clip_transform_recorder.h
+++ b/ui/compositor/clip_transform_recorder.h
@@ -40,8 +40,13 @@ class COMPOSITOR_EXPORT ClipTransformRecorder {
   void Transform(const gfx::Transform& transform);
 
  private:
+  enum Closer {
+    CLIP_RECT,
+    CLIP_PATH,
+    TRANSFORM,
+  };
   const PaintContext& context_;
-  std::vector<cc::DisplayItem*> closers_;
+  std::vector<Closer> closers_;
 
   DISALLOW_COPY_AND_ASSIGN(ClipTransformRecorder);
 };