Fallback to IPv6 if IPv4 adb port not available.

chrome/test/chromedriver/net/adb_client_socket.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 "chrome/test/chromedriver/net/adb_client_socket.h"
 
 #include <stddef.h>
 
 #include "base/bind.h"
 #include "base/compiler_specific.h"
@@ skipping 347 matching lines @@
   new HttpOverAdbSocket(port, serial, socket_name, request_path,
       callback);
 }
 
 AdbClientSocket::AdbClientSocket(int port) : port_(port) {}
 
 AdbClientSocket::~AdbClientSocket() {
 }
 
 void AdbClientSocket::Connect(const net::CompletionCallback& callback) {
-  net::AddressList address_list = net::AddressList::CreateFromIPAddress(
-      net::IPAddress::IPv4Localhost(), port_);
+  net::IPAddressList list = {net::IPAddress::IPv4Localhost(),
+                             net::IPAddress::IPv6Localhost()};

[samuong, 2016/09/21 15:07:34]

Would it be better to resolve "localhost"? On IPv4-only or IPv6-only hosts, this
will just resolve to 127.0.0.1 or ::1, instead of both. You could use
ResolveHost() from chrome/test/chromedriver/net/websocket.cc (but you'd need to
move it out of its anonymous namespace, maybe put it in
chrome/test/chromedriver/net/net_util.cc).

+  net::AddressList ip_list = net::AddressList::CreateFromIPAddressList(
+      list, "localhost");
+  net::AddressList address_list = net::AddressList::CopyWithPort(
+      ip_list, port_);
+
   socket_.reset(new net::TCPClientSocket(address_list, NULL, NULL,
                                          net::NetLog::Source()));
   int result = socket_->Connect(callback);
   if (result != net::ERR_IO_PENDING)
     callback.Run(result);
 }
 
 void AdbClientSocket::SendCommand(const std::string& command,
                                   bool is_void,
                                   bool has_length,
@@ skipping 146 matching lines @@
                                     base::Unretained(this),
                                     callback,
                                     new_response,
                                     response_buffer,
                                     bytes_left));
   if (result > 0)
     OnResponseData(callback, new_response, response_buffer, bytes_left, result);
   else if (result != net::ERR_IO_PENDING)
     callback.Run(net::OK, new_response);
 }