Reland of [chromedriver] Listen on IPv6 on IPv6-only hosts (part 2).

chrome/test/chromedriver/server/chromedriver_server.cc

 // 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.
 
 #include <stddef.h>
 #include <stdint.h>
 #include <stdio.h>
 
 #include <locale>
 #include <memory>
@@ skipping 59 matching lines @@
   explicit HttpServer(const HttpRequestHandlerFunc& handle_request_func)
       : handle_request_func_(handle_request_func),
         weak_factory_(this) {}
 
   ~HttpServer() override {}
 
   bool Start(uint16_t port, bool allow_remote) {
     std::unique_ptr<net::ServerSocket> server_socket(
         new net::TCPServerSocket(NULL, net::NetLog::Source()));
     if (ListenOnIPv4(server_socket.get(), port, allow_remote) != net::OK) {
-      // If we fail to listen on IPv4, try using an IPv6 address. This will work
-      // on an IPv6-only host, but we will be IPv4-only on dual-stack hosts.
+      // This will work on an IPv6-only host, but we will be IPv4-only on
+      // dual-stack hosts.
       // TODO(samuong): change this to listen on both IPv4 and IPv6.
-      if (ListenOnIPv6(server_socket.get(), port, allow_remote) != net::OK)
+      VLOG(0) << "listen on IPv4 failed, trying IPv6";
+      if (ListenOnIPv6(server_socket.get(), port, allow_remote) != net::OK) {
+        VLOG(1) << "listen on both IPv4 and IPv6 failed, giving up";
         return false;
+      }
     }
     server_.reset(new net::HttpServer(std::move(server_socket), this));
     net::IPEndPoint address;
     return server_->GetLocalAddress(&address) == net::OK;
   }
 
   // Overridden from net::HttpServer::Delegate:
   void OnConnect(int connection_id) override {
     server_->SetSendBufferSize(connection_id, kBufferSize);
     server_->SetReceiveBufferSize(connection_id, kBufferSize);
@@ skipping 232 matching lines @@
   }
 
   if (!InitLogging()) {
     printf("Unable to initialize logging. Exiting...\n");
     return 1;
   }
   RunServer(port, allow_remote, whitelisted_ips, url_base, adb_port,
             std::move(port_server));
   return 0;
 }