thermald: update for libchrome uprev

- Use DictionaryValue::SetWithoutPathExpansion.
- Remove ScopedVector, use std::vector<std::uniuqe_ptr<X>> instead.
- Migrate MockTimer to MockRepeatingTimer.
- Migrate base::MessageLoop::QuitWhenIdle to
base::RunLoop::QuitWhenIdleClosure in unittest.

BUG=chromium:909719
TEST=unittest of thermald

Change-Id: Iae2b82681f9157b6240fa99d8061b1132380230e
Reviewed-on: https://chrome-internal-review.googlesource.com/c/chromeos/thermald/+/2366387
Commit-Queue: Qijiang Fan <fqj@google.com>
Tested-by: Qijiang Fan <fqj@google.com>
Reviewed-by: Hidehiko Abe <hidehiko@chromium.org>