`size_t` in `mojo::DataPipe[Consumer|Producer]Handle`: /chromeos.

This CL makes use of the new `size_t`-based APIs in the remaining
directories like `//components`, `//extensions`, or `//storage`.
See https://crrev.com/c/5414148 for motivation.

This CL may have introduced new integer conversions - in those cases the
CL attempts to have well-defined behavior (e.g. using
`base::checked_cast`).  OTOH, this CL did *not* attempt to fix old
integer operations (e.g. old `int` => `uint32_t` / `size_t` conversions,
or old additions that may potentially overflow).

This CL was uploaded by git cl split.

R=wutao@chromium.org

Bug: 40284755
Change-Id: I41d3362ba59b22280b6d26eb799c0f160bf40058
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5462444
Reviewed-by: Tao Wu <wutao@chromium.org>
Commit-Queue: Łukasz Anforowicz <lukasza@chromium.org>
Auto-Submit: Łukasz Anforowicz <lukasza@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1288961}