Use ThreadChecker in HistogramDeltaSerialization class.

There's a suspicion that this code might be being used from multiple threads. Add a ThreadChecker to make sure this isn't happening.

NOTE: These checks will still only be active in debug builds, but if they pass all the bots (that do run with dchecks on) and for developer builds, then I think it's pretty safe to assume there's no issue here. But good to have the precaution.

BUG=554011

Review URL: https://codereview.chromium.org/1463013002

Cr-Commit-Position: refs/heads/master@{#360689}


CrOS-Libchrome-Original-Commit: 0b6761ff0d1339e11707b6459152396320acc1b8
2 files changed
tree: 67f07abe07ac759a18b62cd948b0e5469e8d3213
  1. base/
  2. build/
  3. components/
  4. dbus/
  5. device/
  6. ipc/
  7. mojo/
  8. testing/
  9. third_party/
  10. ui/