Fix NamedProxyLauncher on Windows.

ipc/ipc_channel_posix.cc

Index: ipc/ipc_channel_posix.cc
diff --git a/ipc/ipc_channel_posix.cc b/ipc/ipc_channel_posix.cc
index 462d442df3b98c82e387c173cb52f02696a24c5b..fe60691d3699533168c590161c0623484116c65c 100644
--- a/ipc/ipc_channel_posix.cc
+++ b/ipc/ipc_channel_posix.cc
@@ -993,6 +993,12 @@ void Channel::ChannelImpl::ResetToAcceptingConnectionState() {
   input_overflow_fds_.clear();
 }
 
+// static
+bool Channel::ChannelImpl::IsNamedServerInitialized(
+    const std::string& channel_id) {
+  return file_util::PathExists(FilePath(channel_id));
+}
+
 // Called by libevent when we can read from the pipe without blocking.
 void Channel::ChannelImpl::OnFileCanReadWithoutBlocking(int fd) {
   bool send_server_hello_msg = false;
@@ -1202,4 +1208,9 @@ void Channel::ResetToAcceptingConnectionState() {
   channel_impl_->ResetToAcceptingConnectionState();
 }
 
+// static
+bool Channel::IsNamedServerInitialized(const std::string& channel_id) {
+  return ChannelImpl::IsNamedServerInitialized(channel_id);
+}
+
 }  // namespace IPC