Get rid of Error out param from SendWithReplyAndBlock.

To make it clearer what is input/output, and also let callers access
errors only for error cases.

BUG=1459945
TEST=Ran tryjob

Change-Id: I9ecb129fbf6c7ac142604e29585b7bc8a61dfca0
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4666670
Commit-Queue: Hidehiko Abe <hidehiko@chromium.org>
Reviewed-by: Ryo Hashimoto <hashimoto@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1166444}
NOKEYCHECK=True
GitOrigin-RevId: ac7a3c54d0c4a22fdef4ff6a06ea86d2eec899ec
5 files changed