Implement the WebRTC MdnsResponderInterface in Chromium.

MdnsResponderInterface is introduced in WebRTC to handle the hostname
generation and resolution of ICE host candidates when concealing their
local IP addresses. For WebRTC in Chromium, we implement it as a client
of the service provided by network::mojom::MdnsResponder.

Bug: 878465
Change-Id: Id7b79694deba0ef308e51f83d6134062ddcb3985
Reviewed-on: https://chromium-review.googlesource.com/c/1206002
Commit-Queue: Qingsi Wang <[email protected]>
Reviewed-by: Sergey Ulanov <[email protected]>
Reviewed-by: Avi Drissman <[email protected]>
Reviewed-by: Jesse Doherty <[email protected]>
Cr-Commit-Position: refs/heads/master@{#605153}
diff --git a/chrome/browser/about_flags.cc b/chrome/browser/about_flags.cc
index 0f97c13..5082a05 100644
--- a/chrome/browser/about_flags.cc
+++ b/chrome/browser/about_flags.cc
@@ -1412,6 +1412,10 @@
      flag_descriptions::kWebrtcNewEncodeCpuLoadEstimatorName,
      flag_descriptions::kWebrtcNewEncodeCpuLoadEstimatorDescription, kOsAll,
      FEATURE_VALUE_TYPE(media::kNewEncodeCpuLoadEstimator)},
+    {"enable-webrtc-hide-local-ips-with-mdns",
+     flag_descriptions::kWebrtcHideLocalIpsWithMdnsName,
+     flag_descriptions::kWebrtcHideLocalIpsWithMdnsDecription, kOsDesktop,
+     FEATURE_VALUE_TYPE(features::kWebRtcHideLocalIpsWithMdns)},
     {"webrtc-unified-plan-by-default",
      flag_descriptions::kWebrtcUnifiedPlanByDefaultName,
      flag_descriptions::kWebrtcUnifiedPlanByDefaultDescription, kOsAll,