Turn ThreadPriority enum into an enum class.

Adding some type safety as it is often used in close
proximity with OS-level raw integer priorities.

Also fixing nomenclature to use CHROMIUM_STYLE_ENUM_NAMES
rather than kGoogleStyleEnumNames:
https://www.chromium.org/developers/coding-style#Naming

And lastly, sorting the declaration order by importance.

TBR=jam
BUG=456903

Review URL: https://codereview.chromium.org/1051863003

Cr-Commit-Position: refs/heads/master@{#323359}


CrOS-Libchrome-Original-Commit: 9a47073b992032eccd980693076a2dfb5dab429d
6 files changed
tree: 42f08e98c0cc6d2e15823c742950f13d17ba855b
  1. base/
  2. build/
  3. components/
  4. dbus/
  5. device/
  6. ipc/
  7. mojo/
  8. testing/
  9. third_party/
  10. ui/