Use std::string instead of mojo::String in //net.

net/BUILD.gn

 # Copyright (c) 2013 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.
 
 import("//build/buildflag_header.gni")
 import("//build/config/chromecast_build.gni")
 import("//build/config/compiler/compiler.gni")
 import("//build/config/crypto.gni")
 import("//build/config/features.gni")
 import("//build/config/ui.gni")
@@ skipping 722 matching lines @@
       "proxy/mojo_proxy_resolver_factory.h",
       "proxy/proxy_resolver_factory_mojo.cc",
       "proxy/proxy_resolver_factory_mojo.h",
       "proxy/proxy_service_mojo.cc",
       "proxy/proxy_service_mojo.h",
     ]
 
     public_deps = [
       ":net_with_v8",
       "//base",
-      "//mojo/common",
       "//mojo/public/cpp/bindings",
       "//net/interfaces",
 
       # NOTE(amistry): As long as we support in-process Mojo v8 PAC, we need
       # this dependency since in_process_mojo_proxy_resolver_factory creates
       # the utility process side Mojo services in the browser process.
       # Ultimately, this will go away when we only support out-of-process.
       ":net_utility_services",
     ]
   }
 
   source_set("net_utility_services") {
     sources = [
       "dns/host_resolver_mojo.cc",
       "dns/host_resolver_mojo.h",
       "proxy/mojo_proxy_resolver_factory_impl.cc",
       "proxy/mojo_proxy_resolver_factory_impl.h",
       "proxy/mojo_proxy_resolver_impl.cc",
       "proxy/mojo_proxy_resolver_impl.h",
       "proxy/mojo_proxy_resolver_v8_tracing_bindings.h",
     ]
 
     deps = [
       ":net_with_v8",
       "//base",
     ]
 
     public_deps = [
       ":net",
-      "//mojo/common",
       "//mojo/public/cpp/bindings",
       "//net/interfaces",
     ]
   }
 }
 
 if (!is_ios && !is_android) {
   executable("cert_verify_tool") {
     testonly = true
     sources = [
@@ skipping 1253 matching lines @@
   sources = [
     "http/http_auth_challenge_tokenizer_fuzzer.cc",
   ]
   deps = [
     ":net_fuzzer_test_support",
     ":test_support",
     "//base",
     "//net",
   ]
 }