cc: Move DisplayItemList::Finalize into a cc.debug category.

This is called frequently and might be skewing parent slice times when
tracing.

R=chrishtr@chromium.org

Cq-Include-Trybots: luci.chromium.try:android_optional_gpu_tests_rel;master.tryserver.blink:linux_trusty_blink_rel
Change-Id: Ibfc3f81b78b191a5a7e1dfc44933796337763ca7
Reviewed-on: https://chromium-review.googlesource.com/1137337Reviewed-by: Chris Harrelson <chrishtr@chromium.org>
Commit-Queue: vmpstr <vmpstr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#575124}

cc/paint/display_item_list.cc

@@ -56,7 +56,8 @@ void DisplayItemList::Raster(SkCanvas* canvas,
 }
 
 void DisplayItemList::Finalize() {
-  TRACE_EVENT0("cc", "DisplayItemList::Finalize");
+  TRACE_EVENT0(TRACE_DISABLED_BY_DEFAULT("cc.debug"),
+               "DisplayItemList::Finalize");
 #if DCHECK_IS_ON()
   // If this fails a call to StartPaint() was not ended.
   DCHECK(!IsPainting());