Move visual rect unioning between paired items to cc::DisplayItemList.

ui/compositor/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/transform_recorder.h"
 
 #include "cc/playback/display_item_list.h"
 #include "cc/playback/transform_display_item.h"
 #include "ui/compositor/paint_context.h"
 
 namespace ui {
 
 TransformRecorder::TransformRecorder(const PaintContext& context)
     : context_(context), transformed_(false) {}
 
 TransformRecorder::~TransformRecorder() {
   if (transformed_)
-    context_.list_->CreateAndAppendItem<cc::EndTransformDisplayItem>(
-        bounds_in_layer_);
+    context_.list_->CreateAndAppendPairedEndItem<cc::EndTransformDisplayItem>();
 }
 
-void TransformRecorder::Transform(const gfx::Transform& transform,
-                                  const gfx::Size& size_in_context) {
+void TransformRecorder::Transform(const gfx::Transform& transform) {
   DCHECK(!transformed_);
-  bounds_in_layer_ = context_.ToLayerSpaceBounds(size_in_context);
-  context_.list_->CreateAndAppendItem<cc::TransformDisplayItem>(
-      bounds_in_layer_, transform);
+  context_.list_->CreateAndAppendPairedBeginItem<cc::TransformDisplayItem>(
+      transform);
   transformed_ = true;
 }
 
 }  // namespace ui