Support finch experiment WebRTC-UDPServerSocketAsync for Windows.

content/browser/renderer_host/p2p/socket_host_udp.cc

Index: content/browser/renderer_host/p2p/socket_host_udp.cc
diff --git a/content/browser/renderer_host/p2p/socket_host_udp.cc b/content/browser/renderer_host/p2p/socket_host_udp.cc
index fd09f7d30534e890287c0e9ee94c614813199351..37e4f9089b5a49442aacf1530ebb950ac2fc73f6 100644
--- a/content/browser/renderer_host/p2p/socket_host_udp.cc
+++ b/content/browser/renderer_host/p2p/socket_host_udp.cc
@@ -109,6 +109,19 @@ bool P2PSocketHostUdp::Init(const net::IPEndPoint& local_address,
                             const P2PHostAndIPEndPoint& remote_address) {
   DCHECK_EQ(state_, STATE_UNINITIALIZED);
 
+#if defined(OS_WIN)
+  // If configured for finch experiment, use nonblocking IO.
+  unsigned int use_nonblocking_io = 0;
+
+  base::StringToUint(
+      base::FieldTrialList::FindFullName(
+          "WebRTC-UDPServerSocketAsync"),
+      &use_nonblocking_io);
+  if (use_nonblocking_io > 0) {

[guoweis_left_chromium, 2015/03/03 17:43:39]

Instead of using 0 to stand for disabled, could we change to "Enabled" and
"Disabled"? You could see WebRTC-IPv6Default as an example.

[John L. Miller, 2015/03/23 14:11:27]

Done.

+    _socket::UseNonBlockingIO();
+  }
+#endif
+
   int result = socket_->Listen(local_address);
   if (result < 0) {
     LOG(ERROR) << "bind() failed: " << result;