Replace QuicString with std::string

R=rch@chromium.org

Change-Id: Iac93b506b5ef2afce24aa0ce3e05c3983028eef0
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1516729
Reviewed-by: Ryan Hamilton <rch@chromium.org>
Commit-Queue: Victor Vasiliev <vasilvv@chromium.org>
Cr-Commit-Position: refs/heads/master@{#639784}
17 files changed