Implementation of ProxyResolver that uses a Mojo service.

net/BUILD.gn

Index: net/BUILD.gn
diff --git a/net/BUILD.gn b/net/BUILD.gn
index bfacab909acbd2cee1391808200f75009d64e3bf..d7a6abf17f469f88459849b9cb6bb9047472c9d3 100644
--- a/net/BUILD.gn
+++ b/net/BUILD.gn
@@ -794,6 +794,9 @@ if (use_v8_in_net && !is_android) {
     sources = [
       "dns/mojo_host_resolver_impl.cc",
       "dns/mojo_host_resolver_impl.h",
+      "proxy/mojo_proxy_resolver_factory.h",
+      "proxy/proxy_resolver_mojo.cc",
+      "proxy/proxy_resolver_mojo.h",
     ]
 
     public_deps = [
@@ -1401,6 +1404,7 @@ if (!is_android && !is_win && !is_mac) {
         "dns/mojo_host_resolver_impl_unittest.cc",
         "proxy/mojo_proxy_resolver_factory_impl_unittest.cc",
         "proxy/mojo_proxy_resolver_impl_unittest.cc",
+        "proxy/proxy_resolver_mojo_unittest.cc",
       ]
     }