GitLab

This CL:
 - introduces Segment to remove ad-hoc AllocateSegment / FreeSegment
   calls,
 - removes the const qualifier from Data to remove mutable from
   members,
 - inlines some functions, and
 - includes miscellaneous algorithmic simplification.

This CL doesn't change the behavior, and is not expected to improve or
regress performance.

Bug: None
Change-Id: If1700dd4ae430edbfbd8985836cd73505d441eb4
Reviewed-on: https://chromium-review.googlesource.com/1127573
Commit-Queue: Yutaka Hirano <yhirano@chromium.org>
Reviewed-by: Florin Malita <fmalita@chromium.org>
Cr-Commit-Position: refs/heads/master@{#573495}