cc: defer dumping display item lists till trace is stopped

Also, only trace individual display items if disabled-by-default-cc.debug.display_items is enabled, as these happen to
result in HUGE traces.

BUG=497796
CQ_INCLUDE_TRYBOTS=tryserver.blink:linux_blink_rel

Review URL: https://codereview.chromium.org/1151653005

Cr-Commit-Position: refs/heads/master@{#335244}

diff --git a/cc/BUILD.gn b/cc/BUILD.gn
index 31eab76..ca2f3d2 100644
--- a/cc/BUILD.gn
+++ b/cc/BUILD.gn

@@ -82,6 +82,8 @@
     "debug/rendering_stats_instrumentation.cc",
     "debug/rendering_stats_instrumentation.h",
     "debug/ring_buffer.h",
+    "debug/traced_display_item_list.cc",
+    "debug/traced_display_item_list.h",
     "debug/traced_picture.cc",
     "debug/traced_picture.h",
     "debug/traced_value.cc",