Reland "Add @NullMarked to chrome/android/j/s/o/c/chrome/browser/download part3"

This is a reland of commit 488399db6726ea3aa925b1b391c382ab59d5ae1a

Original change's description:
> Add @NullMarked to chrome/android/j/s/o/c/chrome/browser/download part3
>
> Bug: 389129271
> Change-Id: I2ba1bcfbe7a02404a84dbe7030ba42ab92ff7612
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6766997
> Reviewed-by: Min Qin <qinmin@chromium.org>
> Reviewed-by: Avi Drissman <avi@chromium.org>
> Auto-Submit: Shu Yang <shuyng@google.com>
> Commit-Queue: Shu Yang <shuyng@google.com>
> Reviewed-by: Andrew Grieve <agrieve@chromium.org>
> Cr-Commit-Position: refs/heads/main@{#1492470}

Bug: 389129271
Change-Id: Ie0203ac52925f889aa0aa7efd959fb2665a3dbd8
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6789026
Reviewed-by: Andrew Grieve <agrieve@chromium.org>
Owners-Override: Andrew Grieve <agrieve@chromium.org>
Commit-Queue: Andrew Grieve <agrieve@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1492804}