The new maptracer provides a timeline visualization of the maps logged with
--trace-maps.

Cq-Include-Trybots: master.tryserver.chromium.linux:linux_chromium_rel_ng
Change-Id: I896d677e1d28ceb7b94e29139d25c1476c8ce157
Reviewed-on: https://chromium-review.googlesource.com/664719Reviewed-by: Mathias Bynens <mathias@chromium.org>
Commit-Queue: Camillo Bruni <cbruni@chromium.org>
Cr-Commit-Position: refs/heads/master@{#50158}