message: Remove deprecated //rtc_base:async_resolver.
  Cr-Commit-Position: refs/heads/master@{#33017}
diff: @@ -667,12 +667,6 @@ rtc_library("rtc_json") {
  }
  }
  -rtc_source_set("async_resolver") {
  - # TODO(bugs.webrtc.org/9987): Remove when downstream clients have
  - # been redirected on //rtc_base:threading.
  - sources = []
  -}
  -
  rtc_library("net_helpers") {
  sources = [
  "net_helpers.cc",
  