Add Mojo interfaces for out-of-process proxy resolver.

net/interfaces/proxy_resolver_service.mojom

+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// Put Mojo definitions into their own namespace to avoid collisions with C++
+// definitions.
+// TODO(amistry): Resolve the conflict between these two sets of definitions.
+module net.interfaces;
+
+import "host_resolver_service.mojom";
+
+// Mirror of net::ProxyServer::Scheme.
+enum ProxyScheme {
+  INVALID,
+  DIRECT,
+  HTTP,
+  SOCKS4,
+  SOCKS5,
+  HTTPS,
+  QUIC,
+};
+
+// Mirror of net::ProxyServer.
+struct ProxyServer {
+  ProxyScheme scheme;
+  string host;
+  uint16 port;
+};
+
+interface ProxyResolverService {
+  SetPacScript(string data) => (int32 result);
+
+  // Use a ProxyResolverRequestClient instead of returning a result so we can
+  // receive load state updates and cancel in-flight requests by destroying the
+  // client.
+  // TODO(amistry): Add BoundNetLog.
+  GetProxyForUrl(string url, ProxyResolverRequestClient client);
+};
+
+interface ProxyResolverRequestClient {
+  ReportResult(int32 error, array<ProxyServer>? proxy_servers);
+};
+
+interface ProxyResolverFactory {
+  // TODO(amistry): Add NetLog and ProxyResolverErrorObserver.
+  CreateResolver(ProxyResolverService& resolver,
+                 HostResolverService host_resolver);
+};