Open socket for NaCl GDB debug stub in browser process.

chrome/browser/nacl_host/nacl_process_host.cc

Index: chrome/browser/nacl_host/nacl_process_host.cc
===================================================================
--- chrome/browser/nacl_host/nacl_process_host.cc	(revision 155316)
+++ chrome/browser/nacl_host/nacl_process_host.cc	(working copy)
@@ -39,6 +39,7 @@
 #include "ipc/ipc_switches.h"
 #include "native_client/src/shared/imc/nacl_imc.h"
 #include "net/base/net_util.h"
+#include "net/base/tcp_listen_socket.h"
 #include "ppapi/proxy/ppapi_messages.h"
 
 #if defined(OS_POSIX)
@@ -633,6 +634,17 @@
   return true;
 }
 
+#if defined(OS_POSIX)
+SocketDescriptor NaClProcessHost::GetDebugStubSocketHandle() {
+  SocketDescriptor s = net::TCPListenSocket::CreateAndBind("127.0.0.1", 4014);

[Mark Seaborn, 2012/09/10 15:39:45]

Nit: Can you make 4014 a named constant?  And comment that this is what NaCl
happened to choose for its debug stub TCP port, but that otherwise it's
arbitrary.

[halyavin, 2012/09/11 11:16:12]

Done.

+  if (listen(s, 1)) {
+    LOG(ERROR) << "Failed to listen debug stub socket";

[Mark Seaborn, 2012/09/10 15:39:45]

Missing a preposition.  Maybe "listen() failed on debug stub socket".

[halyavin, 2012/09/11 11:16:12]

Done.

+    return net::TCPListenSocket::kInvalidSocket;
+  }
+  return s;
+}
+#endif
+
 bool NaClProcessHost::StartNaClExecution() {
   NaClBrowser* nacl_browser = NaClBrowser::GetInstance();
 
@@ -660,6 +672,16 @@
   if (!ShareHandleToSelLdr(data.handle, irt_file, false, &params.handles))
     return false;
 
+#if defined(OS_POSIX)
+  if (enable_debug_stub_) {

[Mark Seaborn, 2012/09/10 15:39:45]

Nit: can you put this after the Mac shared memory block, because it's less
essential?

[halyavin, 2012/09/11 11:16:12]

Done.

+    SocketDescriptor server_socket = GetDebugStubSocketHandle();
+    if (server_socket != net::TCPListenSocket::kInvalidSocket) {
+      params.debug_stub_server_socket =
+          nacl::FileDescriptor(server_socket, true);
+    }
+  }
+#endif
+
 #if defined(OS_MACOSX)
   // For dynamic loading support, NaCl requires a file descriptor that
   // was created in /tmp, since those created with shm_open() are not