[jumbo] Inlined a duplicate function GetWorkerThreadIPCMessageSender

A second GetWorkerThreadIPCMessageSender appeared which caused
some (non default) jumbo builds to fail because they ended up
in the same translation unit.

Since they are mostly there to save writing a long expression,
I just inlined them to get past the clash. Alternatives would have
been to rename one of them, or (better) move them to a shared place
so everyone can take advantage of the code.

Bug: 939096

Change-Id: I25b506fb6306c8e023bb39138b91300a48d2c48c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1511400
Commit-Queue: Devlin <rdevlin.cronin@chromium.org>
Auto-Submit: Daniel Bratell <bratell@opera.com>
Reviewed-by: Devlin <rdevlin.cronin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#639128}
2 files changed