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..28af6cf31f8f435ba42832607209b793d08ab942 100644
--- a/chrome/test/chromedriver/net/adb_client_socket.cc
+++ b/chrome/test/chromedriver/net/adb_client_socket.cc
@@ -365,8 +365,13 @@ 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);