cc: Use a ListContainer for DisplayItemList to reduce allocations.

ui/compositor/clip_transform_recorder.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 "ui/compositor/clip_transform_recorder.h"
 
 #include "cc/resources/clip_display_item.h"
 #include "cc/resources/clip_path_display_item.h"
 #include "cc/resources/display_item_list.h"
 #include "cc/resources/transform_display_item.h"
 #include "ui/compositor/paint_context.h"
 #include "ui/gfx/canvas.h"
 #include "ui/gfx/path.h"
 
 namespace ui {
 
 ClipTransformRecorder::ClipTransformRecorder(const PaintContext& context)
     : context_(context) {
   if (context_.canvas_)
     context_.canvas_->Save();
 }
 
 ClipTransformRecorder::~ClipTransformRecorder() {
   if (context_.canvas_)
     context_.canvas_->Restore();
-  for (auto it = closers_.rbegin(); it != closers_.rend(); ++it)
-    context_.list_->AppendItem(make_scoped_ptr(*it));
+  for (Closer c : closers_) {
+    switch (c) {
+      case CLIP_RECT:
+        context_.list_->CreateAndAppendItem<cc::EndClipDisplayItem>();
+        break;
+      case CLIP_PATH:
+        context_.list_->CreateAndAppendItem<cc::EndClipPathDisplayItem>();
+        break;
+      case TRANSFORM:
+        context_.list_->CreateAndAppendItem<cc::EndTransformDisplayItem>();
+        break;
+    }
+  }
 }
 
 void ClipTransformRecorder::ClipRect(const gfx::Rect& clip_rect) {
   if (context_.list_) {
-    context_.list_->AppendItem(
-        cc::ClipDisplayItem::Create(clip_rect, std::vector<SkRRect>()));
-    closers_.push_back(cc::EndClipDisplayItem::Create().release());
+    auto* item = context_.list_->CreateAndAppendItem<cc::ClipDisplayItem>();
+    item->SetNew(clip_rect, std::vector<SkRRect>());
+    closers_.push_back(CLIP_RECT);
   } else {
     context_.canvas_->ClipRect(clip_rect);
   }
 }
 
 void ClipTransformRecorder::ClipPath(const gfx::Path& clip_path) {
   bool anti_alias = false;
   if (context_.list_) {
-    context_.list_->AppendItem(cc::ClipPathDisplayItem::Create(
-        clip_path, SkRegion::kIntersect_Op, anti_alias));
-    closers_.push_back(cc::EndClipPathDisplayItem::Create().release());
+    auto* item = context_.list_->CreateAndAppendItem<cc::ClipPathDisplayItem>();
+    item->SetNew(clip_path, SkRegion::kIntersect_Op, anti_alias);
+    closers_.push_back(CLIP_PATH);
   } else {
     context_.canvas_->ClipPath(clip_path, anti_alias);
   }
 }
 
 void ClipTransformRecorder::ClipPathWithAntiAliasing(
     const gfx::Path& clip_path) {
   bool anti_alias = true;
   if (context_.list_) {
-    context_.list_->AppendItem(cc::ClipPathDisplayItem::Create(
-        clip_path, SkRegion::kIntersect_Op, anti_alias));
-    closers_.push_back(cc::EndClipPathDisplayItem::Create().release());
+    auto* item = context_.list_->CreateAndAppendItem<cc::ClipPathDisplayItem>();
+    item->SetNew(clip_path, SkRegion::kIntersect_Op, anti_alias);
+    closers_.push_back(CLIP_PATH);
   } else {
     context_.canvas_->ClipPath(clip_path, anti_alias);
   }
 }
 
 void ClipTransformRecorder::Transform(const gfx::Transform& transform) {
   if (context_.list_) {
-    context_.list_->AppendItem(cc::TransformDisplayItem::Create(transform));
-    closers_.push_back(cc::EndTransformDisplayItem::Create().release());
+    auto* item =
+        context_.list_->CreateAndAppendItem<cc::TransformDisplayItem>();
+    item->SetNew(transform);
+    closers_.push_back(TRANSFORM);
   } else {
     context_.canvas_->Transform(transform);
   }
 }
 
 }  // namespace ui