Changes imported from Abseil "staging" branch:
Changes imported from Abseil "staging" branch:

  - bb743d8b2017dc1ac181e9d2a90728b45eef344b Internal change. by Daniel Katz <katzdm@google.com>
  - a884af8e2bd70818168aad693b70b8fe98e96bcb Rearrange file comment. by Alex Strelnikov <strel@google.com>
  - 5ed241ef4d5bdc1ef52f7bca9c6ff42d0448e9f4 Internal change. by Alex Strelnikov <strel@google.com>
  - 04d44c8982d7b3077cae5e6189cb512818ce016b Add experiment documentation for MallocExtension API. by Chris Kennelly <ckennelly@google.com>

GitOrigin-RevId: bb743d8b2017dc1ac181e9d2a90728b45eef344b
Change-Id: Ia3ac079fc16b421a0f36be7dc0167045b92e417d

abseil/abseil-cpp,firebase/abseil-cpp,firebase/abseil-cpp,abseil/abseil-cpp,abseil/abseil-cpp,firebase/abseil-cpp,firebase/abseil-cpp,abseil/abseil-cpp