commit 3bc7dce54257dc862bd8515972ac95d8f78b088c
author tzik <tzik@chromium.org> Wed Jul 25 01:56:01 2018
committer Commit Bot <commit-bot@chromium.org> Wed Jul 25 01:56:01 2018
tree a6454780b9f2eb0fe409e063038c8f84a015345c
parent 92346b15a53c4bd520c3e9fc78adbe94b6d19bed

Avoid touching ExtendedAuthenticatorImpl's ref count before its fully constructed

ExtendedAuthenticatorImpl is a ref counted object. Its first reference
is taken by base::Bind in its constructor, and the reference is passed
to GetSystemSalt to do an asynchronous task.
However, if GetSystemSalt impl drops the passed callback soon, (e.g.
by PostTask failure), the reference to ExtendedAuthenticatorImpl is
gone and the instance is destroyed, even before the construction has
completed. That is, `new ExtendedAuthenticatorImpl` might return a
stale pointer on the previous code.

This CL adds a static constructor to ExtendedAuthenticatorImpl, and
moves the problematic part out of the constructor.

Bug: 866456
Change-Id: I377acc8a753c01a79a4cf09617bfa3b0f6aa923f
Reviewed-on: https://chromium-review.googlesource.com/1148164
Reviewed-by: Antoine Labour <piman@chromium.org>
Commit-Queue: Taiju Tsuiki <tzik@chromium.org>
Cr-Commit-Position: refs/heads/master@{#577766}