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

cc/test/fake_content_layer_client.cc

Index: cc/test/fake_content_layer_client.cc
diff --git a/cc/test/fake_content_layer_client.cc b/cc/test/fake_content_layer_client.cc
index d1b1537af32b6edd94f8127dd6e8adb60269e974..597eb021dae75afbb5a7e5bea44418440628f601 100644
--- a/cc/test/fake_content_layer_client.cc
+++ b/cc/test/fake_content_layer_client.cc
@@ -65,25 +65,24 @@ FakeContentLayerClient::PaintContentsToDisplayList(
     const SkPaint& paint = it->second;
     canvas = sk_ref_sp(recorder.beginRecording(gfx::RectFToSkRect(draw_rect)));
     canvas->drawRect(gfx::RectFToSkRect(draw_rect), paint);
-    display_list->CreateAndAppendItem<DrawingDisplayItem>(
+    display_list->CreateAndAppendDrawingItem<DrawingDisplayItem>(
         ToEnclosingRect(draw_rect), recorder.finishRecordingAsPicture());
   }
 
   for (ImageVector::const_iterator it = draw_images_.begin();
        it != draw_images_.end(); ++it) {
     if (!it->transform.IsIdentity()) {
-      display_list->CreateAndAppendItem<TransformDisplayItem>(PaintableRegion(),
-                                                              it->transform);
+      display_list->CreateAndAppendPairedBeginItem<TransformDisplayItem>(
+          it->transform);
     }
     canvas = sk_ref_sp(
         recorder.beginRecording(it->image->width(), it->image->height()));
     canvas->drawImage(it->image.get(), it->point.x(), it->point.y(),
                       &it->paint);
-    display_list->CreateAndAppendItem<DrawingDisplayItem>(
+    display_list->CreateAndAppendDrawingItem<DrawingDisplayItem>(
         PaintableRegion(), recorder.finishRecordingAsPicture());
     if (!it->transform.IsIdentity()) {
-      display_list->CreateAndAppendItem<EndTransformDisplayItem>(
-          PaintableRegion());
+      display_list->CreateAndAppendPairedEndItem<EndTransformDisplayItem>();
     }
   }
 
@@ -95,7 +94,7 @@ FakeContentLayerClient::PaintContentsToDisplayList(
       paint.setColor(red ? SK_ColorRED : SK_ColorBLUE);
       canvas = sk_ref_sp(recorder.beginRecording(gfx::RectToSkRect(draw_rect)));
       canvas->drawIRect(gfx::RectToSkIRect(draw_rect), paint);
-      display_list->CreateAndAppendItem<DrawingDisplayItem>(
+      display_list->CreateAndAppendDrawingItem<DrawingDisplayItem>(
           draw_rect, recorder.finishRecordingAsPicture());
       draw_rect.Inset(1, 1);
     }