Raster display item lists via a visual rect RTree.

cc/test/fake_display_list_raster_source.cc

Index: cc/test/fake_display_list_raster_source.cc
diff --git a/cc/test/fake_display_list_raster_source.cc b/cc/test/fake_display_list_raster_source.cc
index 163559b2f5045796cb162241df2ce1c153cb0e33..2cbee6ab2eff87d2702591c5cefae01b698c446c 100644
--- a/cc/test/fake_display_list_raster_source.cc
+++ b/cc/test/fake_display_list_raster_source.cc
@@ -29,6 +29,10 @@ FakeDisplayListRasterSource::CreateFilled(const gfx::Size& size) {
   red_paint.setColor(SK_ColorRED);
   recording_source->add_draw_rect_with_paint(gfx::Rect(size), red_paint);
 
+  // TODO(wkorman): enne@ has various changes here that look like they're just
+  // hacks to test specific performance items. Omitting for now. See
+  // http://crrev.com/1459003003 for detail.
+
   gfx::Size smaller_size(size.width() - 10, size.height() - 10);
   SkPaint green_paint;
   green_paint.setColor(SK_ColorGREEN);