dbus: Use randomly generated string as a TestService's service name

To run tests parallelly.

BUG=571274
TEST=dbus_unittests

Review URL: https://codereview.chromium.org/1559873005

Cr-Commit-Position: refs/heads/master@{#367499}


CrOS-Libchrome-Original-Commit: 067d84f52f2ec47c2614108be6bf0e11552eb34b
6 files changed
tree: ffedf37119eea8d51c3083f41829d44684d688be
  1. base/
  2. build/
  3. components/
  4. dbus/
  5. device/
  6. ipc/
  7. mojo/
  8. testing/
  9. third_party/
  10. ui/