Fallback to IPv6 if IPv4 adb port not available.

chrome/test/chromedriver/net/adb_client_socket.cc

Index: chrome/test/chromedriver/net/adb_client_socket.cc
diff --git a/chrome/test/chromedriver/net/adb_client_socket.cc b/chrome/test/chromedriver/net/adb_client_socket.cc
index 9a5a672c6bc7e69fc06f35237c67cd837b01f100..5c9115bcb441fba89377a21121ed2b0b2eba7926 100644
--- a/chrome/test/chromedriver/net/adb_client_socket.cc
+++ b/chrome/test/chromedriver/net/adb_client_socket.cc
@@ -370,6 +370,15 @@ void AdbClientSocket::Connect(const net::CompletionCallback& callback) {
   socket_.reset(new net::TCPClientSocket(address_list, NULL, NULL,

[pmarks, 2016/09/20 00:42:13]

It looks like TCPClientSocket already supports connecting to a list of IP
addresses.  Can you pass it a list instead of implementing your own fallback?

[lepton, 2016/09/20 08:04:11]

Done.

                                          net::NetLog::Source()));
   int result = socket_->Connect(callback);
+  if (result == net::ERR_ADDRESS_UNREACHABLE) {
+      VLOG(0) << "connect to IPv4 failed, trying IPv6";
+      address_list =
+          net::AddressList::CreateFromIPAddress(net::IPAddress::IPv6Localhost(),
+                                                port_);
+      socket_.reset(new net::TCPClientSocket(address_list, NULL, NULL,
+                                             net::NetLog::Source()));
+      result = socket_->Connect(callback);
+  }
   if (result != net::ERR_IO_PENDING)
     callback.Run(result);
 }