heap: Make GCInfo a POD

As a drive-by return a tuple of string and flag for an object's name to
easily figure out wheter the object should be considered internal or
not.

Bug: 936797
Change-Id: Icd6efc709b46b48ac6944d3b814ffa72906b55e0
Reviewed-on: https://chromium-review.googlesource.com/c/1493911
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Cr-Commit-Position: refs/heads/master@{#636482}
12 files changed