cc: Use a ListContainer for DisplayItemList to reduce allocations.

cc/blink/web_display_item_list_impl.cc

Index: cc/blink/web_display_item_list_impl.cc
diff --git a/cc/blink/web_display_item_list_impl.cc b/cc/blink/web_display_item_list_impl.cc
index 2bad804cb54a89469e2e0d9cdee2573fa96c2725..7bd983c94904c2fc6b37a19009c0244fc976110c 100644
--- a/cc/blink/web_display_item_list_impl.cc
+++ b/cc/blink/web_display_item_list_impl.cc
@@ -31,8 +31,9 @@ WebDisplayItemListImpl::WebDisplayItemListImpl(
 }
 
 void WebDisplayItemListImpl::appendDrawingItem(const SkPicture* picture) {
-  display_item_list_->AppendItem(cc::DrawingDisplayItem::Create(
-      skia::SharePtr(const_cast<SkPicture*>(picture))));
+  auto* item =
+      display_item_list_->CreateAndAppendItem<cc::DrawingDisplayItem>();
+  item->SetNew(skia::SharePtr(const_cast<SkPicture*>(picture)));
 }
 
 void WebDisplayItemListImpl::appendClipItem(
@@ -42,42 +43,47 @@ void WebDisplayItemListImpl::appendClipItem(
   for (size_t i = 0; i < rounded_clip_rects.size(); ++i) {
     rounded_rects.push_back(rounded_clip_rects[i]);
   }
-  display_item_list_->AppendItem(
-      cc::ClipDisplayItem::Create(clip_rect, rounded_rects));
+  auto* item = display_item_list_->CreateAndAppendItem<cc::ClipDisplayItem>();
+  item->SetNew(clip_rect, rounded_rects);
 }
 
 void WebDisplayItemListImpl::appendEndClipItem() {
-  display_item_list_->AppendItem(cc::EndClipDisplayItem::Create());
+  display_item_list_->CreateAndAppendItem<cc::EndClipDisplayItem>();
 }
 
 void WebDisplayItemListImpl::appendClipPathItem(const SkPath& clip_path,
                                                 SkRegion::Op clip_op,
                                                 bool antialias) {
-  display_item_list_->AppendItem(
-      cc::ClipPathDisplayItem::Create(clip_path, clip_op, antialias));
+  auto* item =
+      display_item_list_->CreateAndAppendItem<cc::ClipPathDisplayItem>();
+  item->SetNew(clip_path, clip_op, antialias);
 }
 
 void WebDisplayItemListImpl::appendEndClipPathItem() {
-  display_item_list_->AppendItem(cc::EndClipPathDisplayItem::Create());
+  display_item_list_->CreateAndAppendItem<cc::EndClipPathDisplayItem>();
 }
 
 void WebDisplayItemListImpl::appendFloatClipItem(
     const blink::WebFloatRect& clip_rect) {
-  display_item_list_->AppendItem(cc::FloatClipDisplayItem::Create(clip_rect));
+  auto* item =
+      display_item_list_->CreateAndAppendItem<cc::FloatClipDisplayItem>();
+  item->SetNew(clip_rect);
 }
 
 void WebDisplayItemListImpl::appendEndFloatClipItem() {
-  display_item_list_->AppendItem(cc::EndFloatClipDisplayItem::Create());
+  display_item_list_->CreateAndAppendItem<cc::EndFloatClipDisplayItem>();
 }
 
 void WebDisplayItemListImpl::appendTransformItem(const SkMatrix44& matrix) {
   gfx::Transform transform;
   transform.matrix() = matrix;
-  display_item_list_->AppendItem(cc::TransformDisplayItem::Create(transform));
+  auto* item =
+      display_item_list_->CreateAndAppendItem<cc::TransformDisplayItem>();
+  item->SetNew(transform);
 }
 
 void WebDisplayItemListImpl::appendEndTransformItem() {
-  display_item_list_->AppendItem(cc::EndTransformDisplayItem::Create());
+  display_item_list_->CreateAndAppendItem<cc::EndTransformDisplayItem>();
 }
 
 void WebDisplayItemListImpl::appendCompositingItem(
@@ -89,13 +95,14 @@ void WebDisplayItemListImpl::appendCompositingItem(
   DCHECK_LE(opacity, 1.f);
   // TODO(ajuma): This should really be rounding instead of flooring the alpha
   // value, but that breaks slimming paint reftests.
-  display_item_list_->AppendItem(cc::CompositingDisplayItem::Create(
-      static_cast<uint8_t>(gfx::ToFlooredInt(255 * opacity)), xfermode, bounds,
-      skia::SharePtr(color_filter)));
+  auto* item =
+      display_item_list_->CreateAndAppendItem<cc::CompositingDisplayItem>();
+  item->SetNew(static_cast<uint8_t>(gfx::ToFlooredInt(255 * opacity)), xfermode,
+               bounds, skia::SharePtr(color_filter));
 }
 
 void WebDisplayItemListImpl::appendEndCompositingItem() {
-  display_item_list_->AppendItem(cc::EndCompositingDisplayItem::Create());
+  display_item_list_->CreateAndAppendItem<cc::EndCompositingDisplayItem>();
 }
 
 void WebDisplayItemListImpl::appendFilterItem(
@@ -103,12 +110,12 @@ void WebDisplayItemListImpl::appendFilterItem(
     const blink::WebFloatRect& bounds) {
   const WebFilterOperationsImpl& filters_impl =
       static_cast<const WebFilterOperationsImpl&>(filters);
-  display_item_list_->AppendItem(
-      cc::FilterDisplayItem::Create(filters_impl.AsFilterOperations(), bounds));
+  auto* item = display_item_list_->CreateAndAppendItem<cc::FilterDisplayItem>();
+  item->SetNew(filters_impl.AsFilterOperations(), bounds);
 }
 
 void WebDisplayItemListImpl::appendEndFilterItem() {
-  display_item_list_->AppendItem(cc::EndFilterDisplayItem::Create());
+  display_item_list_->CreateAndAppendItem<cc::EndFilterDisplayItem>();
 }
 
 void WebDisplayItemListImpl::appendScrollItem(