message: Allow webrtc mac cross compile
  Chromium side changes:
  Cr-Commit-Position: refs/heads/master@{#33424}
diff: @@ -34,7 +34,8 @@ ignore_elf32_limitations = true
  # Use bundled hermetic Xcode installation maintainted by Chromium,
  # except for local iOS builds where it's unsupported.
  -if (host_os == "mac") {
  +# Allow for mac cross compile on linux machines.
  +if (host_os == "mac" || host_os == "linux") {
  _result = exec_script("//build/mac/should_use_hermetic_xcode.py",
  [ target_os ],
  "value")
  