Use base::AlignedHeapArray and updated file API in io_benchmark

No functionality change.

Bug: 435317390
Change-Id: Ia1b0b037d5dd52c2bf191bb674a5196659c201d0
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/7212670
Commit-Queue: Andrew Grieve <[email protected]>
Reviewed-by: Andrew Grieve <[email protected]>
Auto-Submit: Jan Keitel <[email protected]>
Cr-Commit-Position: refs/heads/main@{#1552147}
NOKEYCHECK=True
GitOrigin-RevId: 9d39dff34405b48ab925ba1a16567803e4fa9316
1 file changed