Allow multiple NaCl modules to be debugged.

components/nacl/browser/nacl_process_host.cc

Index: components/nacl/browser/nacl_process_host.cc
diff --git a/components/nacl/browser/nacl_process_host.cc b/components/nacl/browser/nacl_process_host.cc
index 2d154f38d986a846756618da10884de75f8dd870..c5fe4e48c295846fcaf664c8b4c902483889ed86 100644
--- a/components/nacl/browser/nacl_process_host.cc
+++ b/components/nacl/browser/nacl_process_host.cc
@@ -664,7 +664,7 @@ void NaClProcessHost::SendMessageToRenderer(
 }
 
 // TCP port we chose for NaCl debug stub. It can be any other number.
-static const int kDebugStubPort = 4014;
+static const int kInitialDebugStubPort = 4014;
 
 #if defined(OS_POSIX)
 net::SocketDescriptor NaClProcessHost::GetDebugStubSocketHandle() {
@@ -672,15 +672,17 @@ net::SocketDescriptor NaClProcessHost::GetDebugStubSocketHandle() {
   net::SocketDescriptor s = net::kInvalidSocket;
   // We allocate currently unused TCP port for debug stub tests. The port
   // number is passed to the test via debug stub port listener.
-  if (nacl_browser->HasGdbDebugStubPortListener()) {
-    int port;
+  int port = kInitialDebugStubPort;
+  s = net::TCPListenSocket::CreateAndBind("127.0.0.1", port);
+  if (s == net::kInvalidSocket) {
     s = net::TCPListenSocket::CreateAndBindAnyPort("127.0.0.1", &port);
-    if (s != net::kInvalidSocket) {
+  }
+  if (s != net::kInvalidSocket) {
+    if (nacl_browser->HasGdbDebugStubPortListener()) {
       nacl_browser->FireGdbDebugStubPortOpened(port);
     }
-  } else {
-    s = net::TCPListenSocket::CreateAndBind("127.0.0.1", kDebugStubPort);
   }
+  process_->SetNaClDebugStubPort(port);
   if (s == net::kInvalidSocket) {
     LOG(ERROR) << "failed to open socket for debug stub";
     return net::kInvalidSocket;