base: Stop passing by non-const references in some more places.

These are mostly unit test changes. There are a fair number of
occurances still, but they are not easy (or possible) to change due
to STL, third_party, or template requirements.

R=Nico
BUG=464816

Review URL: https://codereview.chromium.org/992083002

Cr-Commit-Position: refs/heads/master@{#319812}


CrOS-Libchrome-Original-Commit: 9fdfd058a7df48c29dd254d8a6a02c8f7c8d31a1
6 files changed
tree: ca5d78b881550ffe1fc113dde5a6b845ed9caf85
  1. base/
  2. build/
  3. components/
  4. dbus/
  5. device/
  6. ipc/
  7. mojo/
  8. testing/
  9. third_party/
  10. ui/