PA: Rename bucket distributions

This CL is trivial. This CL renames
`PartitionRoot::BucketDistribution::kDefault` to `kNeutral` and removes
some allusions to "alternate" bucket distributions.

`kNeutral` is in contrast to `kDenser` and to the deprecated `kCoarser`
(see https://crrev.com/c/4373791). `kDefault` is a less descriptive
name, as it only describes the starting state of PartitionAlloc.
Clients can optionally switch to the denser distribution.

Because of the prevalance of the `kDenser` distribution (non-browser
processes and 32-bit Android excepted), the "default" designation is
best left to higher levels, e.g. `partition_alloc_features`.

This CL does not touch the (now defunct) feature flag infrastructure.

Memo: server-side config was removed in revision 530243413.

Bug: 1238858
Change-Id: I89b5b14b0d024ee9cdfce9e904b6f8faf911f235
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4710168
Commit-Queue: Takashi Sakamoto <tasak@google.com>
Reviewed-by: Thiabaud Engelbrecht <thiabaud@google.com>
Auto-Submit: Kalvin Lee <kdlee@chromium.org>
Reviewed-by: Takashi Sakamoto <tasak@google.com>
Cr-Commit-Position: refs/heads/main@{#1174560}
NOKEYCHECK=True
GitOrigin-RevId: d0dfb8c5d8b912965e588d830d02840b3279f898
1 file changed