GitLab

Operator << of std::stringstream returns a reference to std::ostream
which has no member function str().

Missed while fixing
https://chromium-review.googlesource.com/c/chromium/src/+/2576877

Bug: 819294
Change-Id: Iba035535eaba9bc01c36a74592b6d94956c45498
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2584774
Commit-Queue: Alan Cutter <alancutter@chromium.org>
Reviewed-by: Alan Cutter <alancutter@chromium.org>
Cr-Commit-Position: refs/heads/master@{#836980}